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Describing Databases with MetaData

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SQLAlchemy 0.8 Documentation

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<h1>SQLAlchemy 0.8 Documentation</h1>

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Search:

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Release: 0.8.3 | Release Date: October 26, 2013

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<ul>

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<li>Prev:

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<a href="schema.html" title="previous chapter">Schema Definition Language</a>

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</li>

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<li>Next:

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<a href="reflection.html" title="next chapter">Reflecting Database Objects</a>

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<a href="../contents.html">Table of Contents</a> |

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<a href="../genindex.html">Index</a>

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| <a href="../_sources/core/metadata.txt">view source

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</li>

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</ul>

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</div>

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<a href="../index.html">SQLAlchemy 0.8 Documentation</a>

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» <a href="index.html" title="SQLAlchemy Core">SQLAlchemy Core</a>

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» <a href="schema.html" title="Schema Definition Language">Schema Definition Language</a>

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»

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Describing Databases with MetaData

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<h2>

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Describing Databases with MetaData

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</h2>

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</div>

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</div>

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<h3><a href="../index.html">Table of Contents</a></h3>

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<ul>

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<li><a class="reference internal" href="#">Describing Databases with MetaData</a><ul>

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<li><a class="reference internal" href="#accessing-tables-and-columns">Accessing Tables and Columns</a></li>

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<li><a class="reference internal" href="#creating-and-dropping-database-tables">Creating and Dropping Database Tables</a></li>

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<li><a class="reference internal" href="#altering-schemas-through-migrations">Altering Schemas through Migrations</a></li>

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<li><a class="reference internal" href="#specifying-the-schema-name">Specifying the Schema Name</a></li>

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<li><a class="reference internal" href="#backend-specific-options">Backend-Specific Options</a></li>

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<li><a class="reference internal" href="#column-table-metadata-api">Column, Table, MetaData API</a></li>

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</ul>

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</li>

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</ul>

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<h4>Previous Topic</h4>

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<a href="schema.html" title="previous chapter">Schema Definition Language</a>

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<h4>Next Topic</h4>

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<a href="reflection.html" title="next chapter">Reflecting Database Objects</a>

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<h1>Describing Databases with MetaData<a class="headerlink" href="#module-sqlalchemy.schema" title="Permalink to this headline">¶</a></h1>

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This section discusses the fundamental <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>, <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a>

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and <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> objects.

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A collection of metadata entities is stored in an object aptly named

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<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>:

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<div class="highlight-python"><div class="highlight"><pre>from sqlalchemy import *

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metadata = MetaData()</pre></div>

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</div>

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<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> is a container object that keeps together

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many different features of a database (or multiple databases) being described.

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To represent a table, use the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> class. Its two

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primary arguments are the table name, then the

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<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> object which it will be associated with.

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The remaining positional arguments are mostly

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<a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a> objects describing each column:

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<div class="highlight-python"><div class="highlight"><pre>user = Table('user', metadata,

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Column('user_id', Integer, primary_key = True),

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Column('user_name', String(16), nullable = False),

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Column('email_address', String(60)),

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Column('password', String(20), nullable = False)

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)</pre></div>

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</div>

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Above, a table called <tt class="docutils literal">user</tt> is described, which contains four columns. The

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primary key of the table consists of the <tt class="docutils literal">user_id</tt> column. Multiple columns

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may be assigned the <tt class="docutils literal">primary_key=True</tt> flag which denotes a multi-column

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primary key, known as a composite primary key.

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Note also that each column describes its datatype using objects corresponding

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to genericized types, such as <a class="reference internal" href="types.html#sqlalchemy.types.Integer" title="sqlalchemy.types.Integer"><tt class="xref py py-class docutils literal">Integer</tt></a> and

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<a class="reference internal" href="types.html#sqlalchemy.types.String" title="sqlalchemy.types.String"><tt class="xref py py-class docutils literal">String</tt></a>. SQLAlchemy features dozens of types of

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varying levels of specificity as well as the ability to create custom types.

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Documentation on the type system can be found at types.

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<h2>Accessing Tables and Columns<a class="headerlink" href="#accessing-tables-and-columns" title="Permalink to this headline">¶</a></h2>

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The <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> object contains all of the schema

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constructs we’ve associated with it. It supports a few methods of accessing

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these table objects, such as the <tt class="docutils literal">sorted_tables</tt> accessor which returns a

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list of each <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> object in order of foreign key

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dependency (that is, each table is preceded by all tables which it

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references):

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<div class="highlight-python"><div class="highlight"><pre>>>> for t in metadata.sorted_tables:

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... print t.name

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user

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user_preference

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invoice

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invoice_item</pre></div>

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</div>

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In most cases, individual <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects have been

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explicitly declared, and these objects are typically accessed directly as

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module-level variables in an application. Once a

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<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> has been defined, it has a full set of

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accessors which allow inspection of its properties. Given the following

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<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> definition:

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<div class="highlight-python"><div class="highlight"><pre>employees = Table('employees', metadata,

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Column('employee_id', Integer, primary_key=True),

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Column('employee_name', String(60), nullable=False),

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Column('employee_dept', Integer, ForeignKey("departments.department_id"))

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)</pre></div>

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</div>

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Note the <a class="reference internal" href="constraints.html#sqlalchemy.schema.ForeignKey" title="sqlalchemy.schema.ForeignKey"><tt class="xref py py-class docutils literal">ForeignKey</tt></a> object used in this table -

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this construct defines a reference to a remote table, and is fully described

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in metadata_foreignkeys. Methods of accessing information about this

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table include:

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<div class="highlight-python"><div class="highlight"><pre># access the column "EMPLOYEE_ID":

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employees.columns.employee_id

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# or just

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employees.c.employee_id

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# via string

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employees.c['employee_id']

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# iterate through all columns

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for c in employees.c:

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print c

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# get the table's primary key columns

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for primary_key in employees.primary_key:

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print primary_key

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# get the table's foreign key objects:

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for fkey in employees.foreign_keys:

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print fkey

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# access the table's MetaData:

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employees.metadata

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# access the table's bound Engine or Connection, if its MetaData is bound:

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employees.bind

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# access a column's name, type, nullable, primary key, foreign key

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employees.c.employee_id.name

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employees.c.employee_id.type

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employees.c.employee_id.nullable

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employees.c.employee_id.primary_key

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employees.c.employee_dept.foreign_keys

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# get the "key" of a column, which defaults to its name, but can

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# be any user-defined string:

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employees.c.employee_name.key

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# access a column's table:

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employees.c.employee_id.table is employees

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# get the table related by a foreign key

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list(employees.c.employee_dept.foreign_keys)[0].column.table</pre></div>

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</div>

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</div>

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<h2>Creating and Dropping Database Tables<a class="headerlink" href="#creating-and-dropping-database-tables" title="Permalink to this headline">¶</a></h2>

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Once you’ve defined some <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects, assuming

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you’re working with a brand new database one thing you might want to do is

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issue CREATE statements for those tables and their related constructs (as an

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aside, it’s also quite possible that you don’t want to do this, if you

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already have some preferred methodology such as tools included with your

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database or an existing scripting system - if that’s the case, feel free to

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skip this section - SQLAlchemy has no requirement that it be used to create

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your tables).

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The usual way to issue CREATE is to use

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<a class="reference internal" href="#sqlalchemy.schema.MetaData.create_all" title="sqlalchemy.schema.MetaData.create_all"><tt class="xref py py-func docutils literal">create_all()</tt></a> on the

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<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> object. This method will issue queries

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that first check for the existence of each individual table, and if not found

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will issue the CREATE statements:

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<div><div class="highlight-python+sql"><div class="highlight"><pre>engine = create_engine('sqlite:///:memory:')

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metadata = MetaData()

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user = Table('user', metadata,

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Column('user_id', Integer, primary_key = True),

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Column('user_name', String(16), nullable = False),

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Column('email_address', String(60), key='email'),

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Column('password', String(20), nullable = False)

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)

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user_prefs = Table('user_prefs', metadata,

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Column('pref_id', Integer, primary_key=True),

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Column('user_id', Integer, ForeignKey("user.user_id"), nullable=False),

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Column('pref_name', String(40), nullable=False),

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Column('pref_value', String(100))

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)

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<a href='#' class='sql_link'>sql</a>metadata.create_all(engine)

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<div class='popup_sql'>PRAGMA table_info(user){}

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CREATE TABLE user(

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user_id INTEGER NOT NULL PRIMARY KEY,

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user_name VARCHAR(16) NOT NULL,

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email_address VARCHAR(60),

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password VARCHAR(20) NOT NULL

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)

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PRAGMA table_info(user_prefs){}

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CREATE TABLE user_prefs(

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pref_id INTEGER NOT NULL PRIMARY KEY,

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user_id INTEGER NOT NULL REFERENCES user(user_id),

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pref_name VARCHAR(40) NOT NULL,

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pref_value VARCHAR(100)

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)</div></pre></div>

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</div>

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</div></blockquote>

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<a class="reference internal" href="#sqlalchemy.schema.MetaData.create_all" title="sqlalchemy.schema.MetaData.create_all"><tt class="xref py py-func docutils literal">create_all()</tt></a> creates foreign key constraints

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between tables usually inline with the table definition itself, and for this

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reason it also generates the tables in order of their dependency. There are

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options to change this behavior such that <tt class="docutils literal">ALTER TABLE</tt> is used instead.

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Dropping all tables is similarly achieved using the

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<a class="reference internal" href="#sqlalchemy.schema.MetaData.drop_all" title="sqlalchemy.schema.MetaData.drop_all"><tt class="xref py py-func docutils literal">drop_all()</tt></a> method. This method does the

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exact opposite of <a class="reference internal" href="#sqlalchemy.schema.MetaData.create_all" title="sqlalchemy.schema.MetaData.create_all"><tt class="xref py py-func docutils literal">create_all()</tt></a> - the

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presence of each table is checked first, and tables are dropped in reverse

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order of dependency.

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Creating and dropping individual tables can be done via the <tt class="docutils literal">create()</tt> and

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<tt class="docutils literal">drop()</tt> methods of <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>. These methods by

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default issue the CREATE or DROP regardless of the table being present:

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<div class="highlight-python+sql"><div class="highlight"><pre>engine = create_engine('sqlite:///:memory:')

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meta = MetaData()

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employees = Table('employees', meta,

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Column('employee_id', Integer, primary_key=True),

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Column('employee_name', String(60), nullable=False, key='name'),

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Column('employee_dept', Integer, ForeignKey("departments.department_id"))

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)

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<a href='#' class='sql_link'>sql</a>employees.create(engine)

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<div class='popup_sql'>CREATE TABLE employees(

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employee_id SERIAL NOT NULL PRIMARY KEY,

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employee_name VARCHAR(60) NOT NULL,

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employee_dept INTEGER REFERENCES departments(department_id)

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)</div></pre></div>

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</div>

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<tt class="docutils literal">drop()</tt> method:

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<div class="highlight-python+sql"><div class="highlight"><pre><a href='#' class='sql_link'>sql</a>employees.drop(engine)

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<div class='popup_sql'>DROP TABLE employee</div></pre></div>

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</div>

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To enable the “check first for the table existing” logic, add the

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<tt class="docutils literal">checkfirst=True</tt> argument to <tt class="docutils literal">create()</tt> or <tt class="docutils literal">drop()</tt>:

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<div class="highlight-python"><div class="highlight"><pre>employees.create(engine, checkfirst=True)

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employees.drop(engine, checkfirst=False)</pre></div>

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</div>

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</div>

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<h2>Altering Schemas through Migrations<a class="headerlink" href="#altering-schemas-through-migrations" title="Permalink to this headline">¶</a></h2>

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While SQLAlchemy directly supports emitting CREATE and DROP statements for schema

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constructs, the ability to alter those constructs, usually via the ALTER statement

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as well as other database-specific constructs, is outside of the scope of SQLAlchemy

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itself. While it’s easy enough to emit ALTER statements and similar by hand,

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such as by passing a string to <a class="reference internal" href="connections.html#sqlalchemy.engine.Connection.execute" title="sqlalchemy.engine.Connection.execute"><tt class="xref py py-meth docutils literal">Connection.execute()</tt></a> or by using the

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<a class="reference internal" href="ddl.html#sqlalchemy.schema.DDL" title="sqlalchemy.schema.DDL"><tt class="xref py py-class docutils literal">DDL</tt></a> construct, it’s a common practice to automate the maintenance of

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database schemas in relation to application code using schema migration tools.

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There are two major migration tools available for SQLAlchemy:

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<li><a class="reference external" href="http://alembic.readthedocs.org">Alembic</a> - Written by the author of SQLAlchemy,

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Alembic features a highly customizable environment and a minimalistic usage pattern,

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supporting such features as transactional DDL, automatic generation of “candidate”

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migrations, an “offline” mode which generates SQL scripts, and support for branch

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resolution.</li>

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<li><a class="reference external" href="http://code.google.com/p/sqlalchemy-migrate/">SQLAlchemy-Migrate</a> - The original

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migration tool for SQLAlchemy, SQLAlchemy-Migrate is widely used and continues

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under active development. SQLAlchemy-Migrate includes features such as

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SQL script generation, ORM class generation, ORM model comparison, and extensive

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support for SQLite migrations.</li>

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</ul>

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</div>

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<h2>Specifying the Schema Name<a class="headerlink" href="#specifying-the-schema-name" title="Permalink to this headline">¶</a></h2>

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Some databases support the concept of multiple schemas. A

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<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> can reference this by specifying the

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<tt class="docutils literal">schema</tt> keyword argument:

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<div class="highlight-python"><div class="highlight"><pre>financial_info = Table('financial_info', meta,

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Column('id', Integer, primary_key=True),

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Column('value', String(100), nullable=False),

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schema='remote_banks'

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)</pre></div>

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</div>

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Within the <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> collection, this table will be

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identified by the combination of <tt class="docutils literal">financial_info</tt> and <tt class="docutils literal">remote_banks</tt>. If

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another table called <tt class="docutils literal">financial_info</tt> is referenced without the

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<tt class="docutils literal">remote_banks</tt> schema, it will refer to a different

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<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>. <a class="reference internal" href="constraints.html#sqlalchemy.schema.ForeignKey" title="sqlalchemy.schema.ForeignKey"><tt class="xref py py-class docutils literal">ForeignKey</tt></a>

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objects can specify references to columns in this table using the form

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<tt class="docutils literal">remote_banks.financial_info.id</tt>.

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The <tt class="docutils literal">schema</tt> argument should be used for any name qualifiers required,

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including Oracle’s “owner” attribute and similar. It also can accommodate a

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dotted name for longer schemes:

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<div class="highlight-python"><div class="highlight"><pre>schema="dbo.scott"</pre></div>

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</div>

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</div>

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<h2>Backend-Specific Options<a class="headerlink" href="#backend-specific-options" title="Permalink to this headline">¶</a></h2>

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<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> supports database-specific options. For

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example, MySQL has different table backend types, including “MyISAM” and

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“InnoDB”. This can be expressed with <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> using

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<tt class="docutils literal">mysql_engine</tt>:

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<div class="highlight-python"><div class="highlight"><pre>addresses = Table('engine_email_addresses', meta,

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Column('address_id', Integer, primary_key = True),

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Column('remote_user_id', Integer, ForeignKey(users.c.user_id)),

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Column('email_address', String(20)),

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mysql_engine='InnoDB'

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)</pre></div>

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</div>

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Other backends may support table-level options as well - these would be

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described in the individual documentation sections for each dialect.

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</div>

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<h2>Column, Table, MetaData API<a class="headerlink" href="#column-table-metadata-api" title="Permalink to this headline">¶</a></h2>

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class <tt class="descclassname">sqlalchemy.schema.</tt><tt class="descname">Column</tt><big>(</big>*args, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">sqlalchemy.schema.SchemaItem</tt></a>, <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnClause" title="sqlalchemy.sql.expression.ColumnClause"><tt class="xref py py-class docutils literal">sqlalchemy.sql.expression.ColumnClause</tt></a>

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Represents a column in a database table.

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<tt class="descname">__eq__</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.__eq__" title="Permalink to this definition">¶</a></dt>

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inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.__eq__" title="sqlalchemy.sql.operators.ColumnOperators.__eq__"><tt class="xref py py-meth docutils literal">__eq__()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

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Implement the <tt class="docutils literal">==</tt> operator.

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In a column context, produces the clause <tt class="docutils literal">a = b</tt>.

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If the target is <tt class="docutils literal">None</tt>, produces <tt class="docutils literal">a IS NULL</tt>.

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</dd></dl>

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<tt class="descname">__init__</tt><big>(</big>*args, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.__init__" title="Permalink to this definition">¶</a></dt>

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<dd>Construct a new <tt class="docutils literal">Column</tt> object.

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<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

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<li>name – The name of this column as represented in the database.

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This argument may be the first positional argument, or specified

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via keyword.

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Names which contain no upper case characters

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will be treated as case insensitive names, and will not be quoted

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unless they are a reserved word. Names with any number of upper

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case characters will be quoted and sent exactly. Note that this

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behavior applies even for databases which standardize upper

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case names as case insensitive such as Oracle.

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The name field may be omitted at construction time and applied

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later, at any time before the Column is associated with a

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<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>. This is to support convenient

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usage within the <a class="reference internal" href="../orm/extensions/declarative.html#module-sqlalchemy.ext.declarative" title="sqlalchemy.ext.declarative"><tt class="xref py py-mod docutils literal">declarative</tt></a> extension.

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</li>

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<li>type_ – The column’s type, indicated using an instance which

454

subclasses <a class="reference internal" href="types.html#sqlalchemy.types.TypeEngine" title="sqlalchemy.types.TypeEngine"><tt class="xref py py-class docutils literal">TypeEngine</tt></a>. If no arguments

455

are required for the type, the class of the type can be sent

456

as well, e.g.:

457

<div class="highlight-python"><div class="highlight"><pre># use a type with arguments

458

Column('data', String(50))

459

460

# use no arguments

461

Column('level', Integer)</pre></div>

462

</div>

463

The <tt class="docutils literal">type</tt> argument may be the second positional argument

464

or specified by keyword.

465

There is partial support for automatic detection of the

466

type based on that of a <a class="reference internal" href="constraints.html#sqlalchemy.schema.ForeignKey" title="sqlalchemy.schema.ForeignKey"><tt class="xref py py-class docutils literal">ForeignKey</tt></a> associated

467

with this column, if the type is specified as <tt class="docutils literal">None</tt>.

468

However, this feature is not fully implemented and

469

may not function in all cases.

470

</li>

471

<li>*args – Additional positional arguments include various

472

<a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">SchemaItem</tt></a> derived constructs which will be applied

473

as options to the column. These include instances of

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<a class="reference internal" href="constraints.html#sqlalchemy.schema.Constraint" title="sqlalchemy.schema.Constraint"><tt class="xref py py-class docutils literal">Constraint</tt></a>, <a class="reference internal" href="constraints.html#sqlalchemy.schema.ForeignKey" title="sqlalchemy.schema.ForeignKey"><tt class="xref py py-class docutils literal">ForeignKey</tt></a>, <a class="reference internal" href="defaults.html#sqlalchemy.schema.ColumnDefault" title="sqlalchemy.schema.ColumnDefault"><tt class="xref py py-class docutils literal">ColumnDefault</tt></a>,

475

and <a class="reference internal" href="defaults.html#sqlalchemy.schema.Sequence" title="sqlalchemy.schema.Sequence"><tt class="xref py py-class docutils literal">Sequence</tt></a>. In some cases an equivalent keyword

476

argument is available such as <tt class="docutils literal">server_default</tt>, <tt class="docutils literal">default</tt>

477

and <tt class="docutils literal">unique</tt>.</li>

478

<li>autoincrement – This flag may be set to <tt class="docutils literal">False</tt> to

479

indicate an integer primary key column that should not be

480

considered to be the “autoincrement” column, that is

481

the integer primary key column which generates values

482

implicitly upon INSERT and whose value is usually returned

483

via the DBAPI cursor.lastrowid attribute. It defaults

484

to <tt class="docutils literal">True</tt> to satisfy the common use case of a table

485

with a single integer primary key column. If the table

486

has a composite primary key consisting of more than one

487

integer column, set this flag to True only on the

488

column that should be considered “autoincrement”.

489

The setting only has an effect for columns which are:

490

<ul>

491

<li>Integer derived (i.e. INT, SMALLINT, BIGINT).</li>

492

<li>Part of the primary key</li>

493

<li>Are not referenced by any foreign keys, unless

494

the value is specified as <tt class="docutils literal">'ignore_fk'</tt><div class="versionadded">

495

New in version 0.7.4.

496

</div>

497

</li>

498

<li>have no server side or client side defaults (with the exception

499

of Postgresql SERIAL).</li>

500

</ul>

501

The setting has these two effects on columns that meet the

502

above criteria:

503

<ul>

504

<li>DDL issued for the column will include database-specific

505

keywords intended to signify this column as an

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“autoincrement” column, such as AUTO INCREMENT on MySQL,

507

SERIAL on Postgresql, and IDENTITY on MS-SQL. It does

508

not issue AUTOINCREMENT for SQLite since this is a

509

special SQLite flag that is not required for autoincrementing

510

behavior. See the SQLite dialect documentation for

511

information on SQLite’s AUTOINCREMENT.</li>

512

<li>The column will be considered to be available as

513

cursor.lastrowid or equivalent, for those dialects which

514

“post fetch” newly inserted identifiers after a row has

515

been inserted (SQLite, MySQL, MS-SQL). It does not have

516

any effect in this regard for databases that use sequences

517

to generate primary key identifiers (i.e. Firebird, Postgresql,

518

Oracle).</li>

519

</ul>

520

521

Changed in version 0.7.4: <tt class="docutils literal">autoincrement</tt> accepts a special value <tt class="docutils literal">'ignore_fk'</tt>

522

to indicate that autoincrementing status regardless of foreign

523

key references. This applies to certain composite foreign key

524

setups, such as the one demonstrated in the ORM documentation

525

at <a class="reference internal" href="../orm/relationships.html#post-update">Rows that point to themselves / Mutually Dependent Rows</a>.

526

</div>

527

</li>

528

<li>default – A scalar, Python callable, or

529

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a> expression representing the

530

default value for this column, which will be invoked upon insert

531

if this column is otherwise not specified in the VALUES clause of

532

the insert. This is a shortcut to using <a class="reference internal" href="defaults.html#sqlalchemy.schema.ColumnDefault" title="sqlalchemy.schema.ColumnDefault"><tt class="xref py py-class docutils literal">ColumnDefault</tt></a> as

533

a positional argument; see that class for full detail on the

534

structure of the argument.

535

Contrast this argument to <tt class="docutils literal">server_default</tt> which creates a

536

default generator on the database side.

537

</li>

538

<li>doc – optional String that can be used by the ORM or similar

539

to document attributes. This attribute does not render SQL

540

comments (a future attribute ‘comment’ will achieve that).</li>

541

<li>key – An optional string identifier which will identify this

542

<tt class="docutils literal">Column</tt> object on the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>. When a key is provided,

543

this is the only identifier referencing the <tt class="docutils literal">Column</tt> within the

544

application, including ORM attribute mapping; the <tt class="docutils literal">name</tt> field

545

is used only when rendering SQL.</li>

546

<li>index – When <tt class="docutils literal">True</tt>, indicates that the column is indexed.

547

This is a shortcut for using a <a class="reference internal" href="constraints.html#sqlalchemy.schema.Index" title="sqlalchemy.schema.Index"><tt class="xref py py-class docutils literal">Index</tt></a> construct on the

548

table. To specify indexes with explicit names or indexes that

549

contain multiple columns, use the <a class="reference internal" href="constraints.html#sqlalchemy.schema.Index" title="sqlalchemy.schema.Index"><tt class="xref py py-class docutils literal">Index</tt></a> construct

550

instead.</li>

551

<li>info – Optional data dictionary which will be populated into the

552

<a class="reference internal" href="#sqlalchemy.schema.SchemaItem.info" title="sqlalchemy.schema.SchemaItem.info"><tt class="xref py py-attr docutils literal">SchemaItem.info</tt></a> attribute of this object.</li>

553

<li>nullable – If set to the default of <tt class="docutils literal">True</tt>, indicates the

554

column will be rendered as allowing NULL, else it’s rendered as

555

NOT NULL. This parameter is only used when issuing CREATE TABLE

556

statements.</li>

557

<li>onupdate – A scalar, Python callable, or

558

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a> representing a

559

default value to be applied to the column within UPDATE

560

statements, which wil be invoked upon update if this column is not

561

present in the SET clause of the update. This is a shortcut to

562

using <a class="reference internal" href="defaults.html#sqlalchemy.schema.ColumnDefault" title="sqlalchemy.schema.ColumnDefault"><tt class="xref py py-class docutils literal">ColumnDefault</tt></a> as a positional argument with

563

<tt class="docutils literal">for_update=True</tt>.</li>

564

<li>primary_key – If <tt class="docutils literal">True</tt>, marks this column as a primary key

565

column. Multiple columns can have this flag set to specify

566

composite primary keys. As an alternative, the primary key of a

567

<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> can be specified via an explicit

568

<a class="reference internal" href="constraints.html#sqlalchemy.schema.PrimaryKeyConstraint" title="sqlalchemy.schema.PrimaryKeyConstraint"><tt class="xref py py-class docutils literal">PrimaryKeyConstraint</tt></a> object.</li>

569

<li>server_default – A <a class="reference internal" href="defaults.html#sqlalchemy.schema.FetchedValue" title="sqlalchemy.schema.FetchedValue"><tt class="xref py py-class docutils literal">FetchedValue</tt></a> instance, str, Unicode

570

or <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.text" title="sqlalchemy.sql.expression.text"><tt class="xref py py-func docutils literal">text()</tt></a> construct representing

571

the DDL DEFAULT value for the column.

572

String types will be emitted as-is, surrounded by single quotes:

573

<div class="highlight-python"><pre>Column('x', Text, server_default="val")

574

575

x TEXT DEFAULT 'val'</pre>

576

</div>

577

A <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.text" title="sqlalchemy.sql.expression.text"><tt class="xref py py-func docutils literal">text()</tt></a> expression will be

578

rendered as-is, without quotes:

579

<div class="highlight-python"><pre>Column('y', DateTime, server_default=text('NOW()'))0

580

581

y DATETIME DEFAULT NOW()</pre>

582

</div>

583

Strings and text() will be converted into a <a class="reference internal" href="defaults.html#sqlalchemy.schema.DefaultClause" title="sqlalchemy.schema.DefaultClause"><tt class="xref py py-class docutils literal">DefaultClause</tt></a>

584

object upon initialization.

585

Use <a class="reference internal" href="defaults.html#sqlalchemy.schema.FetchedValue" title="sqlalchemy.schema.FetchedValue"><tt class="xref py py-class docutils literal">FetchedValue</tt></a> to indicate that an already-existing

586

column will generate a default value on the database side which

587

will be available to SQLAlchemy for post-fetch after inserts. This

588

construct does not specify any DDL and the implementation is left

589

to the database, such as via a trigger.

590

</li>

591

<li>server_onupdate – A <a class="reference internal" href="defaults.html#sqlalchemy.schema.FetchedValue" title="sqlalchemy.schema.FetchedValue"><tt class="xref py py-class docutils literal">FetchedValue</tt></a> instance

592

representing a database-side default generation function. This

593

indicates to SQLAlchemy that a newly generated value will be

594

available after updates. This construct does not specify any DDL

595

and the implementation is left to the database, such as via a

596

trigger.</li>

597

<li>quote – Force quoting of this column’s name on or off,

598

corresponding to <tt class="docutils literal">True</tt> or <tt class="docutils literal">False</tt>. When left at its default

599

of <tt class="docutils literal">None</tt>, the column identifier will be quoted according to

600

whether the name is case sensitive (identifiers with at least one

601

upper case character are treated as case sensitive), or if it’s a

602

reserved word. This flag is only needed to force quoting of a

603

reserved word which is not known by the SQLAlchemy dialect.</li>

604

<li>unique – When <tt class="docutils literal">True</tt>, indicates that this column contains a

605

unique constraint, or if <tt class="docutils literal">index</tt> is <tt class="docutils literal">True</tt> as well, indicates

606

that the <a class="reference internal" href="constraints.html#sqlalchemy.schema.Index" title="sqlalchemy.schema.Index"><tt class="xref py py-class docutils literal">Index</tt></a> should be created with the unique flag.

607

To specify multiple columns in the constraint/index or to specify

608

an explicit name, use the <a class="reference internal" href="constraints.html#sqlalchemy.schema.UniqueConstraint" title="sqlalchemy.schema.UniqueConstraint"><tt class="xref py py-class docutils literal">UniqueConstraint</tt></a> or

609

<a class="reference internal" href="constraints.html#sqlalchemy.schema.Index" title="sqlalchemy.schema.Index"><tt class="xref py py-class docutils literal">Index</tt></a> constructs explicitly.</li>

610

<li>system – When <tt class="docutils literal">True</tt>, indicates this is a “system” column,

611

that is a column which is automatically made available by the

612

database, and should not be included in the columns list for a

613

<tt class="docutils literal">CREATE TABLE</tt> statement.

614

For more elaborate scenarios where columns should be conditionally

615

rendered differently on different backends, consider custom

616

compilation rules for <a class="reference internal" href="ddl.html#sqlalchemy.schema.CreateColumn" title="sqlalchemy.schema.CreateColumn"><tt class="xref py py-class docutils literal">CreateColumn</tt></a>.

617

618

<dt>..versionadded:: 0.8.3 Added the <tt class="docutils literal">system=True</tt> parameter to</dt>

619

<dd><a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a>.</dd>

620

</dl>

621

</li>

622

</ul>

623

</td>

624

</tr>

625

</tbody>

626

</table>

627

</dd></dl>

628

629

630

631

<tt class="descname">__le__</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.__le__" title="Permalink to this definition">¶</a></dt>

632

633

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.__le__" title="sqlalchemy.sql.operators.ColumnOperators.__le__"><tt class="xref py py-meth docutils literal">__le__()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

634

Implement the <tt class="docutils literal"><=</tt> operator.

635

In a column context, produces the clause <tt class="docutils literal">a <= b</tt>.

636

</dd></dl>

637

638

639

640

<tt class="descname">__lt__</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.__lt__" title="Permalink to this definition">¶</a></dt>

641

642

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.__lt__" title="sqlalchemy.sql.operators.ColumnOperators.__lt__"><tt class="xref py py-meth docutils literal">__lt__()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

643

Implement the <tt class="docutils literal"><</tt> operator.

644

In a column context, produces the clause <tt class="docutils literal">a < b</tt>.

645

</dd></dl>

646

647

648

649

<tt class="descname">__ne__</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.__ne__" title="Permalink to this definition">¶</a></dt>

650

651

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.__ne__" title="sqlalchemy.sql.operators.ColumnOperators.__ne__"><tt class="xref py py-meth docutils literal">__ne__()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

652

Implement the <tt class="docutils literal">!=</tt> operator.

653

In a column context, produces the clause <tt class="docutils literal">a != b</tt>.

654

If the target is <tt class="docutils literal">None</tt>, produces <tt class="docutils literal">a IS NOT NULL</tt>.

655

</dd></dl>

656

657

658

659

<tt class="descname">anon_label</tt><a class="headerlink" href="#sqlalchemy.schema.Column.anon_label" title="Permalink to this definition">¶</a></dt>

660

661

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement.anon_label" title="sqlalchemy.sql.expression.ColumnElement.anon_label"><tt class="xref py py-attr docutils literal">anon_label</tt></a> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

662

provides a constant ‘anonymous label’ for this ColumnElement.

663

This is a label() expression which will be named at compile time.

664

The same label() is returned each time anon_label is called so

665

that expressions can reference anon_label multiple times, producing

666

the same label name at compile time.

667

the compiler uses this function automatically at compile time

668

for expressions that are known to be ‘unnamed’ like binary

669

expressions and function calls.

670

</dd></dl>

671

672

673

674

<tt class="descname">append_foreign_key</tt><big>(</big>fk<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.append_foreign_key" title="Permalink to this definition">¶</a></dt>

675

676

677

678

679

680

681

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.asc" title="sqlalchemy.sql.operators.ColumnOperators.asc"><tt class="xref py py-meth docutils literal">asc()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

682

Produce a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.asc" title="sqlalchemy.sql.expression.asc"><tt class="xref py py-func docutils literal">asc()</tt></a> clause against the

683

parent object.

684

</dd></dl>

685

686

687

688

<tt class="descname">base_columns</tt><a class="headerlink" href="#sqlalchemy.schema.Column.base_columns" title="Permalink to this definition">¶</a></dt>

689

690

inherited from the <tt class="xref py py-attr docutils literal">base_columns</tt> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

691

</dd></dl>

692

693

694

695

<tt class="descname">between</tt><big>(</big>cleft, cright<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.between" title="Permalink to this definition">¶</a></dt>

696

697

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.between" title="sqlalchemy.sql.operators.ColumnOperators.between"><tt class="xref py py-meth docutils literal">between()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

698

Produce a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.between" title="sqlalchemy.sql.expression.between"><tt class="xref py py-func docutils literal">between()</tt></a> clause against

699

the parent object, given the lower and upper range.

700

</dd></dl>

701

702

703

704

705

706

707

708

709

<tt class="descname">collate</tt><big>(</big>collation<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.collate" title="Permalink to this definition">¶</a></dt>

710

711

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.collate" title="sqlalchemy.sql.operators.ColumnOperators.collate"><tt class="xref py py-meth docutils literal">collate()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

712

Produce a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.collate" title="sqlalchemy.sql.expression.collate"><tt class="xref py py-func docutils literal">collate()</tt></a> clause against

713

the parent object, given the collation string.

714

</dd></dl>

715

716

717

718

<tt class="descname">comparator</tt><a class="headerlink" href="#sqlalchemy.schema.Column.comparator" title="Permalink to this definition">¶</a></dt>

719

720

inherited from the <tt class="xref py py-attr docutils literal">comparator</tt> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

721

</dd></dl>

722

723

724

725

<tt class="descname">compare</tt><big>(</big>other, use_proxies=False, equivalents=None, **kw<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.compare" title="Permalink to this definition">¶</a></dt>

726

727

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement.compare" title="sqlalchemy.sql.expression.ColumnElement.compare"><tt class="xref py py-meth docutils literal">compare()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

728

Compare this ColumnElement to another.

729

Special arguments understood:

730

731

732

733

734

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

735

<li>use_proxies – when True, consider two columns that

736

share a common base column as equivalent (i.e. shares_lineage())</li>

737

<li>equivalents – a dictionary of columns as keys mapped to sets

738

of columns. If the given “other” column is present in this

739

dictionary, if any of the columns in the corresponding set() pass the

740

comparison test, the result is True. This is used to expand the

741

comparison to other columns that may be known to be equivalent to

742

this one via foreign key or other criterion.</li>

743

</ul>

744

</td>

745

</tr>

746

</tbody>

747

</table>

748

</dd></dl>

749

750

751

752

<tt class="descname">compile</tt><big>(</big>bind=None, dialect=None, **kw<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.compile" title="Permalink to this definition">¶</a></dt>

753

754

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement.compile" title="sqlalchemy.sql.expression.ClauseElement.compile"><tt class="xref py py-meth docutils literal">compile()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a></div>

755

Compile this SQL expression.

756

The return value is a <a class="reference internal" href="internals.html#sqlalchemy.engine.interfaces.Compiled" title="sqlalchemy.engine.interfaces.Compiled"><tt class="xref py py-class docutils literal">Compiled</tt></a> object.

757

Calling <tt class="docutils literal">str()</tt> or <tt class="docutils literal">unicode()</tt> on the returned value will yield a

758

string representation of the result. The

759

<a class="reference internal" href="internals.html#sqlalchemy.engine.interfaces.Compiled" title="sqlalchemy.engine.interfaces.Compiled"><tt class="xref py py-class docutils literal">Compiled</tt></a> object also can return a

760

dictionary of bind parameter names and values

761

using the <tt class="docutils literal">params</tt> accessor.

762

763

764

765

766

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

767

<li>bind – An <tt class="docutils literal">Engine</tt> or <tt class="docutils literal">Connection</tt> from which a

768

<tt class="docutils literal">Compiled</tt> will be acquired. This argument takes precedence over

769

this <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>‘s bound engine, if any.</li>

770

<li>column_keys – Used for INSERT and UPDATE statements, a list of

771

column names which should be present in the VALUES clause of the

772

compiled statement. If <tt class="docutils literal">None</tt>, all columns from the target table

773

object are rendered.</li>

774

<li>dialect – A <tt class="docutils literal">Dialect</tt> instance from which a <tt class="docutils literal">Compiled</tt>

775

will be acquired. This argument takes precedence over the <cite>bind</cite>

776

argument as well as this <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>‘s bound engine, if

777

any.</li>

778

<li>inline – Used for INSERT statements, for a dialect which does

779

not support inline retrieval of newly generated primary key

780

columns, will force the expression used to create the new primary

781

key value to be rendered inline within the INSERT statement’s

782

VALUES clause. This typically refers to Sequence execution but may

783

also refer to any server-side default generation function

784

associated with a primary key <cite>Column</cite>.</li>

785

</ul>

786

</td>

787

</tr>

788

</tbody>

789

</table>

790

</dd></dl>

791

792

793

794

<tt class="descname">concat</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.concat" title="Permalink to this definition">¶</a></dt>

795

796

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.concat" title="sqlalchemy.sql.operators.ColumnOperators.concat"><tt class="xref py py-meth docutils literal">concat()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

797

Implement the ‘concat’ operator.

798

In a column context, produces the clause <tt class="docutils literal">a || b</tt>,

799

or uses the <tt class="docutils literal">concat()</tt> operator on MySQL.

800

</dd></dl>

801

802

803

804

<tt class="descname">contains</tt><big>(</big>other, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.contains" title="Permalink to this definition">¶</a></dt>

805

806

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.contains" title="sqlalchemy.sql.operators.ColumnOperators.contains"><tt class="xref py py-meth docutils literal">contains()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

807

Implement the ‘contains’ operator.

808

In a column context, produces the clause <tt class="docutils literal">LIKE '%<other>%'</tt>

809

</dd></dl>

810

811

812

813

814

<dd>Create a copy of this <tt class="docutils literal">Column</tt>, unitialized.

815

This is used in <tt class="docutils literal">Table.tometadata</tt>.

816

</dd></dl>

817

818

819

820

<tt class="descname">default</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Column.default" title="Permalink to this definition">¶</a></dt>

821

822

823

824

825

826

827

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.desc" title="sqlalchemy.sql.operators.ColumnOperators.desc"><tt class="xref py py-meth docutils literal">desc()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

828

Produce a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.desc" title="sqlalchemy.sql.expression.desc"><tt class="xref py py-func docutils literal">desc()</tt></a> clause against the

829

parent object.

830

</dd></dl>

831

832

833

834

<tt class="descname">description</tt><a class="headerlink" href="#sqlalchemy.schema.Column.description" title="Permalink to this definition">¶</a></dt>

835

836

inherited from the <tt class="xref py py-attr docutils literal">description</tt> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnClause" title="sqlalchemy.sql.expression.ColumnClause"><tt class="xref py py-class docutils literal">ColumnClause</tt></a></div>

837

</dd></dl>

838

839

840

841

<tt class="descname">dispatch</tt><a class="headerlink" href="#sqlalchemy.schema.Column.dispatch" title="Permalink to this definition">¶</a></dt>

842

<dd>alias of <tt class="xref py py-class docutils literal">DDLEventsDispatch</tt>

843

</dd></dl>

844

845

846

847

<tt class="descname">distinct</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.distinct" title="Permalink to this definition">¶</a></dt>

848

849

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.distinct" title="sqlalchemy.sql.operators.ColumnOperators.distinct"><tt class="xref py py-meth docutils literal">distinct()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

850

Produce a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.distinct" title="sqlalchemy.sql.expression.distinct"><tt class="xref py py-func docutils literal">distinct()</tt></a> clause against the

851

parent object.

852

</dd></dl>

853

854

855

856

<tt class="descname">endswith</tt><big>(</big>other, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.endswith" title="Permalink to this definition">¶</a></dt>

857

858

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.endswith" title="sqlalchemy.sql.operators.ColumnOperators.endswith"><tt class="xref py py-meth docutils literal">endswith()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

859

Implement the ‘endswith’ operator.

860

In a column context, produces the clause <tt class="docutils literal">LIKE '%<other>'</tt>

861

</dd></dl>

862

863

864

865

<tt class="descname">expression</tt><a class="headerlink" href="#sqlalchemy.schema.Column.expression" title="Permalink to this definition">¶</a></dt>

866

867

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement.expression" title="sqlalchemy.sql.expression.ColumnElement.expression"><tt class="xref py py-attr docutils literal">expression</tt></a> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

868

Return a column expression.

869

Part of the inspection interface; returns self.

870

</dd></dl>

871

872

873

874

<tt class="descname">foreign_keys</tt> = []<a class="headerlink" href="#sqlalchemy.schema.Column.foreign_keys" title="Permalink to this definition">¶</a></dt>

875

876

877

878

879

<tt class="descname">get_children</tt><big>(</big>schema_visitor=False, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.get_children" title="Permalink to this definition">¶</a></dt>

880

881

882

883

884

<tt class="descname">ilike</tt><big>(</big>other, escape=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.ilike" title="Permalink to this definition">¶</a></dt>

885

886

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.ilike" title="sqlalchemy.sql.operators.ColumnOperators.ilike"><tt class="xref py py-meth docutils literal">ilike()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

887

Implement the <tt class="docutils literal">ilike</tt> operator.

888

In a column context, produces the clause <tt class="docutils literal">a ILIKE other</tt>.

889

E.g.:

890

<div class="highlight-python"><div class="highlight"><pre>select([sometable]).where(sometable.c.column.ilike("%foobar%"))</pre></div>

891

</div>

892

893

894

895

896

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

897

<li>other – expression to be compared</li>

898

<li>escape – optional escape character, renders the <tt class="docutils literal">ESCAPE</tt>

899

keyword, e.g.:

900

<div class="highlight-python"><div class="highlight"><pre>somecolumn.ilike("foo/%bar", escape="/")</pre></div>

901

</div>

902

</li>

903

</ul>

904

</td>

905

</tr>

906

</tbody>

907

</table>

908

909

See also

910

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.like" title="sqlalchemy.sql.operators.ColumnOperators.like"><tt class="xref py py-meth docutils literal">ColumnOperators.like()</tt></a>

911

</div>

912

</dd></dl>

913

914

915

916

<tt class="descname">in_</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.in_" title="Permalink to this definition">¶</a></dt>

917

918

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.in_" title="sqlalchemy.sql.operators.ColumnOperators.in_"><tt class="xref py py-meth docutils literal">in_()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

919

Implement the <tt class="docutils literal">in</tt> operator.

920

In a column context, produces the clause <tt class="docutils literal">a IN other</tt>.

921

“other” may be a tuple/list of column expressions,

922

or a <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><tt class="xref py py-func docutils literal">select()</tt></a> construct.

923

</dd></dl>

924

925

926

927

928

929

inherited from the <a class="reference internal" href="#sqlalchemy.schema.SchemaItem.info" title="sqlalchemy.schema.SchemaItem.info"><tt class="xref py py-attr docutils literal">info</tt></a> attribute of <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">SchemaItem</tt></a></div>

930

Info dictionary associated with the object, allowing user-defined

931

data to be associated with this <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">SchemaItem</tt></a>.

932

The dictionary is automatically generated when first accessed.

933

It can also be specified in the constructor of some objects,

934

such as <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> and <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a>.

935

</dd></dl>

936

937

938

939

<tt class="descname">is_</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.is_" title="Permalink to this definition">¶</a></dt>

940

941

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.is_" title="sqlalchemy.sql.operators.ColumnOperators.is_"><tt class="xref py py-meth docutils literal">is_()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

942

Implement the <tt class="docutils literal">IS</tt> operator.

943

Normally, <tt class="docutils literal">IS</tt> is generated automatically when comparing to a

944

value of <tt class="docutils literal">None</tt>, which resolves to <tt class="docutils literal">NULL</tt>. However, explicit

945

usage of <tt class="docutils literal">IS</tt> may be desirable if comparing to boolean values

946

on certain platforms.

947

948

New in version 0.7.9.

949

</div>

950

951

See also

952

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.isnot" title="sqlalchemy.sql.operators.ColumnOperators.isnot"><tt class="xref py py-meth docutils literal">ColumnOperators.isnot()</tt></a>

953

</div>

954

</dd></dl>

955

956

957

958

<tt class="descname">is_clause_element</tt> = True<a class="headerlink" href="#sqlalchemy.schema.Column.is_clause_element" title="Permalink to this definition">¶</a></dt>

959

960

961

962

963

<tt class="descname">is_selectable</tt> = False<a class="headerlink" href="#sqlalchemy.schema.Column.is_selectable" title="Permalink to this definition">¶</a></dt>

964

965

966

967

968

<tt class="descname">isnot</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.isnot" title="Permalink to this definition">¶</a></dt>

969

970

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.isnot" title="sqlalchemy.sql.operators.ColumnOperators.isnot"><tt class="xref py py-meth docutils literal">isnot()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

971

Implement the <tt class="docutils literal">IS NOT</tt> operator.

972

Normally, <tt class="docutils literal">IS NOT</tt> is generated automatically when comparing to a

973

value of <tt class="docutils literal">None</tt>, which resolves to <tt class="docutils literal">NULL</tt>. However, explicit

974

usage of <tt class="docutils literal">IS NOT</tt> may be desirable if comparing to boolean values

975

on certain platforms.

976

977

New in version 0.7.9.

978

</div>

979

980

See also

981

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.is_" title="sqlalchemy.sql.operators.ColumnOperators.is_"><tt class="xref py py-meth docutils literal">ColumnOperators.is_()</tt></a>

982

</div>

983

</dd></dl>

984

985

986

987

<tt class="descname">label</tt><big>(</big>name<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.label" title="Permalink to this definition">¶</a></dt>

988

989

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement.label" title="sqlalchemy.sql.expression.ColumnElement.label"><tt class="xref py py-meth docutils literal">label()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

990

Produce a column label, i.e. <tt class="docutils literal"><columnname> AS <name></tt>.

991

This is a shortcut to the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.label" title="sqlalchemy.sql.expression.label"><tt class="xref py py-func docutils literal">label()</tt></a> function.

992

if ‘name’ is None, an anonymous label name will be generated.

993

</dd></dl>

994

995

996

997

<tt class="descname">like</tt><big>(</big>other, escape=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.like" title="Permalink to this definition">¶</a></dt>

998

999

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.like" title="sqlalchemy.sql.operators.ColumnOperators.like"><tt class="xref py py-meth docutils literal">like()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1000

Implement the <tt class="docutils literal">like</tt> operator.

1001

In a column context, produces the clause <tt class="docutils literal">a LIKE other</tt>.

1002

E.g.:

1003

<div class="highlight-python"><div class="highlight"><pre>select([sometable]).where(sometable.c.column.like("%foobar%"))</pre></div>

1004

</div>

1005

1006

1007

1008

1009

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1010

<li>other – expression to be compared</li>

1011

<li>escape – optional escape character, renders the <tt class="docutils literal">ESCAPE</tt>

1012

keyword, e.g.:

1013

<div class="highlight-python"><div class="highlight"><pre>somecolumn.like("foo/%bar", escape="/")</pre></div>

1014

</div>

1015

</li>

1016

</ul>

1017

</td>

1018

</tr>

1019

</tbody>

1020

</table>

1021

1022

See also

1023

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.ilike" title="sqlalchemy.sql.operators.ColumnOperators.ilike"><tt class="xref py py-meth docutils literal">ColumnOperators.ilike()</tt></a>

1024

</div>

1025

</dd></dl>

1026

1027

1028

1029

<tt class="descname">match</tt><big>(</big>other, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.match" title="Permalink to this definition">¶</a></dt>

1030

1031

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.match" title="sqlalchemy.sql.operators.ColumnOperators.match"><tt class="xref py py-meth docutils literal">match()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1032

Implements the ‘match’ operator.

1033

In a column context, this produces a MATCH clause, i.e.

1034

<tt class="docutils literal">MATCH '<other>'</tt>. The allowed contents of <tt class="docutils literal">other</tt>

1035

are database backend specific.

1036

</dd></dl>

1037

1038

1039

1040

<tt class="descname">notilike</tt><big>(</big>other, escape=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.notilike" title="Permalink to this definition">¶</a></dt>

1041

1042

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.notilike" title="sqlalchemy.sql.operators.ColumnOperators.notilike"><tt class="xref py py-meth docutils literal">notilike()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1043

implement the <tt class="docutils literal">NOT ILIKE</tt> operator.

1044

This is equivalent to using negation with

1045

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.ilike" title="sqlalchemy.sql.operators.ColumnOperators.ilike"><tt class="xref py py-meth docutils literal">ColumnOperators.ilike()</tt></a>, i.e. <tt class="docutils literal">~x.ilike(y)</tt>.

1046

1047

New in version 0.8.

1048

</div>

1049

1050

See also

1051

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.ilike" title="sqlalchemy.sql.operators.ColumnOperators.ilike"><tt class="xref py py-meth docutils literal">ColumnOperators.ilike()</tt></a>

1052

</div>

1053

</dd></dl>

1054

1055

1056

1057

<tt class="descname">notin_</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.notin_" title="Permalink to this definition">¶</a></dt>

1058

1059

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.notin_" title="sqlalchemy.sql.operators.ColumnOperators.notin_"><tt class="xref py py-meth docutils literal">notin_()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1060

implement the <tt class="docutils literal">NOT IN</tt> operator.

1061

This is equivalent to using negation with <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.in_" title="sqlalchemy.sql.operators.ColumnOperators.in_"><tt class="xref py py-meth docutils literal">ColumnOperators.in_()</tt></a>,

1062

i.e. <tt class="docutils literal">~x.in_(y)</tt>.

1063

1064

New in version 0.8.

1065

</div>

1066

1067

See also

1068

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.in_" title="sqlalchemy.sql.operators.ColumnOperators.in_"><tt class="xref py py-meth docutils literal">ColumnOperators.in_()</tt></a>

1069

</div>

1070

</dd></dl>

1071

1072

1073

1074

<tt class="descname">notlike</tt><big>(</big>other, escape=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.notlike" title="Permalink to this definition">¶</a></dt>

1075

1076

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.notlike" title="sqlalchemy.sql.operators.ColumnOperators.notlike"><tt class="xref py py-meth docutils literal">notlike()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1077

implement the <tt class="docutils literal">NOT LIKE</tt> operator.

1078

This is equivalent to using negation with

1079

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.like" title="sqlalchemy.sql.operators.ColumnOperators.like"><tt class="xref py py-meth docutils literal">ColumnOperators.like()</tt></a>, i.e. <tt class="docutils literal">~x.like(y)</tt>.

1080

1081

New in version 0.8.

1082

</div>

1083

1084

See also

1085

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.like" title="sqlalchemy.sql.operators.ColumnOperators.like"><tt class="xref py py-meth docutils literal">ColumnOperators.like()</tt></a>

1086

</div>

1087

</dd></dl>

1088

1089

1090

1091

<tt class="descname">nullsfirst</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.nullsfirst" title="Permalink to this definition">¶</a></dt>

1092

1093

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.nullsfirst" title="sqlalchemy.sql.operators.ColumnOperators.nullsfirst"><tt class="xref py py-meth docutils literal">nullsfirst()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1094

Produce a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.nullsfirst" title="sqlalchemy.sql.expression.nullsfirst"><tt class="xref py py-func docutils literal">nullsfirst()</tt></a> clause against the

1095

parent object.

1096

</dd></dl>

1097

1098

1099

1100

<tt class="descname">nullslast</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.nullslast" title="Permalink to this definition">¶</a></dt>

1101

1102

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.nullslast" title="sqlalchemy.sql.operators.ColumnOperators.nullslast"><tt class="xref py py-meth docutils literal">nullslast()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1103

Produce a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.nullslast" title="sqlalchemy.sql.expression.nullslast"><tt class="xref py py-func docutils literal">nullslast()</tt></a> clause against the

1104

parent object.

1105

</dd></dl>

1106

1107

1108

1109

<tt class="descname">onupdate</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Column.onupdate" title="Permalink to this definition">¶</a></dt>

1110

1111

1112

1113

1114

<tt class="descname">op</tt><big>(</big>opstring, precedence=0<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.op" title="Permalink to this definition">¶</a></dt>

1115

1116

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.Operators.op" title="sqlalchemy.sql.operators.Operators.op"><tt class="xref py py-meth docutils literal">op()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.Operators" title="sqlalchemy.sql.operators.Operators"><tt class="xref py py-class docutils literal">Operators</tt></a></div>

1117

produce a generic operator function.

1118

e.g.:

1119

<div class="highlight-python"><div class="highlight"><pre>somecolumn.op("*")(5)</pre></div>

1120

</div>

1121

produces:

1122

<div class="highlight-python"><div class="highlight"><pre>somecolumn * 5</pre></div>

1123

</div>

1124

This function can also be used to make bitwise operators explicit. For

1125

example:

1126

<div class="highlight-python"><div class="highlight"><pre>somecolumn.op('&')(0xff)</pre></div>

1127

</div>

1128

is a bitwise AND of the value in <tt class="docutils literal">somecolumn</tt>.

1129

1130

1131

1132

1133

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1134

<li>operator – a string which will be output as the infix operator

1135

between this element and the expression passed to the

1136

generated function.</li>

1137

<li>precedence – precedence to apply to the operator, when

1138

parenthesizing expressions. A lower number will cause the expression

1139

to be parenthesized when applied against another operator with

1140

higher precedence. The default value of <tt class="docutils literal">0</tt> is lower than all

1141

operators except for the comma (<tt class="docutils literal">,</tt>) and <tt class="docutils literal">AS</tt> operators.

1142

A value of 100 will be higher or equal to all operators, and -100

1143

will be lower than or equal to all operators.

1144

1145

New in version 0.8: - added the ‘precedence’ argument.

1146

</div>

1147

</li>

1148

</ul>

1149

</td>

1150

</tr>

1151

</tbody>

1152

</table>

1153

1154

See also

1155

<a class="reference internal" href="types.html#types-operators">Redefining and Creating New Operators</a>

1156

</div>

1157

</dd></dl>

1158

1159

1160

1161

<tt class="descname">operate</tt><big>(</big>op, *other, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.operate" title="Permalink to this definition">¶</a></dt>

1162

1163

inherited from the <tt class="xref py py-meth docutils literal">operate()</tt> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

1164

</dd></dl>

1165

1166

1167

1168

<tt class="descname">params</tt><big>(</big>*optionaldict, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.params" title="Permalink to this definition">¶</a></dt>

1169

1170

inherited from the <tt class="xref py py-meth docutils literal">params()</tt> method of <tt class="xref py py-class docutils literal">Immutable</tt></div>

1171

</dd></dl>

1172

1173

1174

1175

<tt class="descname">primary_key</tt> = False<a class="headerlink" href="#sqlalchemy.schema.Column.primary_key" title="Permalink to this definition">¶</a></dt>

1176

1177

1178

1179

1180

<tt class="descname">proxy_set</tt><a class="headerlink" href="#sqlalchemy.schema.Column.proxy_set" title="Permalink to this definition">¶</a></dt>

1181

1182

inherited from the <tt class="xref py py-attr docutils literal">proxy_set</tt> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

1183

</dd></dl>

1184

1185

1186

1187

<tt class="descname">quote</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Column.quote" title="Permalink to this definition">¶</a></dt>

1188

1189

1190

1191

1192

<tt class="descname">references</tt><big>(</big>column<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.references" title="Permalink to this definition">¶</a></dt>

1193

<dd>Return True if this Column references the given column via foreign

1194

key.

1195

</dd></dl>

1196

1197

1198

1199

<tt class="descname">reverse_operate</tt><big>(</big>op, other, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.reverse_operate" title="Permalink to this definition">¶</a></dt>

1200

1201

inherited from the <tt class="xref py py-meth docutils literal">reverse_operate()</tt> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

1202

</dd></dl>

1203

1204

1205

1206

<tt class="descname">self_group</tt><big>(</big>against=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.self_group" title="Permalink to this definition">¶</a></dt>

1207

1208

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement.self_group" title="sqlalchemy.sql.expression.ClauseElement.self_group"><tt class="xref py py-meth docutils literal">self_group()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a></div>

1209

Apply a ‘grouping’ to this <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>.

1210

This method is overridden by subclasses to return a

1211

“grouping” construct, i.e. parenthesis. In particular

1212

it’s used by “binary” expressions to provide a grouping

1213

around themselves when placed into a larger expression,

1214

as well as by <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><tt class="xref py py-func docutils literal">select()</tt></a> constructs when placed into

1215

the FROM clause of another <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><tt class="xref py py-func docutils literal">select()</tt></a>. (Note that

1216

subqueries should be normally created using the

1217

<tt class="xref py py-func docutils literal">Select.alias()</tt> method, as many platforms require

1218

nested SELECT statements to be named).

1219

As expressions are composed together, the application of

1220

<a class="reference internal" href="#sqlalchemy.schema.Column.self_group" title="sqlalchemy.schema.Column.self_group"><tt class="xref py py-meth docutils literal">self_group()</tt></a> is automatic - end-user code should never

1221

need to use this method directly. Note that SQLAlchemy’s

1222

clause constructs take operator precedence into account -

1223

so parenthesis might not be needed, for example, in

1224

an expression like <tt class="docutils literal">x OR (y AND z)</tt> - AND takes precedence

1225

over OR.

1226

The base <a class="reference internal" href="#sqlalchemy.schema.Column.self_group" title="sqlalchemy.schema.Column.self_group"><tt class="xref py py-meth docutils literal">self_group()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>

1227

just returns self.

1228

</dd></dl>

1229

1230

1231

1232

<tt class="descname">server_default</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Column.server_default" title="Permalink to this definition">¶</a></dt>

1233

1234

1235

1236

1237

<tt class="descname">server_onupdate</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Column.server_onupdate" title="Permalink to this definition">¶</a></dt>

1238

1239

1240

1241

1242

<tt class="descname">shares_lineage</tt><big>(</big>othercolumn<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.shares_lineage" title="Permalink to this definition">¶</a></dt>

1243

1244

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement.shares_lineage" title="sqlalchemy.sql.expression.ColumnElement.shares_lineage"><tt class="xref py py-meth docutils literal">shares_lineage()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

1245

Return True if the given <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a>

1246

has a common ancestor to this <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a>.

1247

</dd></dl>

1248

1249

1250

1251

<tt class="descname">startswith</tt><big>(</big>other, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.startswith" title="Permalink to this definition">¶</a></dt>

1252

1253

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators.startswith" title="sqlalchemy.sql.operators.ColumnOperators.startswith"><tt class="xref py py-meth docutils literal">startswith()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">ColumnOperators</tt></a></div>

1254

Implement the <tt class="docutils literal">startwith</tt> operator.

1255

In a column context, produces the clause <tt class="docutils literal">LIKE '<other>%'</tt>

1256

</dd></dl>

1257

1258

1259

1260

<tt class="descname">supports_execution</tt> = False<a class="headerlink" href="#sqlalchemy.schema.Column.supports_execution" title="Permalink to this definition">¶</a></dt>

1261

1262

1263

1264

1265

<tt class="descname">table</tt><a class="headerlink" href="#sqlalchemy.schema.Column.table" title="Permalink to this definition">¶</a></dt>

1266

1267

inherited from the <tt class="xref py py-attr docutils literal">table</tt> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnClause" title="sqlalchemy.sql.expression.ColumnClause"><tt class="xref py py-class docutils literal">ColumnClause</tt></a></div>

1268

</dd></dl>

1269

1270

1271

1272

<tt class="descname">timetuple</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Column.timetuple" title="Permalink to this definition">¶</a></dt>

1273

1274

1275

1276

1277

1278

1279

inherited from the <tt class="xref py py-attr docutils literal">type</tt> attribute of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a></div>

1280

</dd></dl>

1281

1282

1283

1284

<tt class="descname">unique_params</tt><big>(</big>*optionaldict, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Column.unique_params" title="Permalink to this definition">¶</a></dt>

1285

1286

inherited from the <tt class="xref py py-meth docutils literal">unique_params()</tt> method of <tt class="xref py py-class docutils literal">Immutable</tt></div>

1287

</dd></dl>

1288

1289

</dd></dl>

1290

1291

1292

1293

class <tt class="descclassname">sqlalchemy.schema.</tt><tt class="descname">MetaData</tt><big>(</big>bind=None, reflect=False, schema=None, quote_schema=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData" title="Permalink to this definition">¶</a></dt>

1294

<dd>Bases: <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">sqlalchemy.schema.SchemaItem</tt></a>

1295

A collection of <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects and their associated schema

1296

constructs.

1297

Holds a collection of <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects as well as

1298

an optional binding to an <a class="reference internal" href="connections.html#sqlalchemy.engine.Engine" title="sqlalchemy.engine.Engine"><tt class="xref py py-class docutils literal">Engine</tt></a> or

1299

<a class="reference internal" href="connections.html#sqlalchemy.engine.Connection" title="sqlalchemy.engine.Connection"><tt class="xref py py-class docutils literal">Connection</tt></a>. If bound, the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects

1300

in the collection and their columns may participate in implicit SQL

1301

execution.

1302

The <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects themselves are stored in the

1303

<tt class="docutils literal">metadata.tables</tt> dictionary.

1304

The <tt class="docutils literal">bind</tt> property may be assigned to dynamically. A common pattern is

1305

to start unbound and then bind later when an engine is available:

1306

<div class="highlight-python"><div class="highlight"><pre>metadata = MetaData()

1307

# define tables

1308

Table('mytable', metadata, ...)

1309

# connect to an engine later, perhaps after loading a URL from a

1310

# configuration file

1311

metadata.bind = an_engine</pre></div>

1312

</div>

1313

MetaData is a thread-safe object after tables have been explicitly defined

1314

or loaded via reflection.

1315

1316

See also

1317

<a class="reference internal" href="#metadata-describing">Describing Databases with MetaData</a> - Introduction to database metadata

1318

</div>

1319

1320

1321

<tt class="descname">__init__</tt><big>(</big>bind=None, reflect=False, schema=None, quote_schema=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.__init__" title="Permalink to this definition">¶</a></dt>

1322

<dd>Create a new MetaData object.

1323

1324

1325

1326

1327

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1328

<li>bind – An Engine or Connection to bind to. May also be a string or URL

1329

instance, these are passed to create_engine() and this MetaData will

1330

be bound to the resulting engine.</li>

1331

<li>reflect – Optional, automatically load all tables from the bound database.

1332

Defaults to False. <tt class="docutils literal">bind</tt> is required when this option is set.

1333

1334

Deprecated since version 0.8: Please use the <a class="reference internal" href="#sqlalchemy.schema.MetaData.reflect" title="sqlalchemy.schema.MetaData.reflect"><tt class="xref py py-meth docutils literal">MetaData.reflect()</tt></a> method.

1335

</div>

1336

</li>

1337

<li>schema – The default schema to use for the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>,

1338

<a class="reference internal" href="defaults.html#sqlalchemy.schema.Sequence" title="sqlalchemy.schema.Sequence"><tt class="xref py py-class docutils literal">Sequence</tt></a>, and other objects associated with this

1339

<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>. Defaults to <tt class="docutils literal">None</tt>.</li>

1340

<li>quote_schema – Sets the <tt class="docutils literal">quote_schema</tt> flag for those <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>,

1341

<a class="reference internal" href="defaults.html#sqlalchemy.schema.Sequence" title="sqlalchemy.schema.Sequence"><tt class="xref py py-class docutils literal">Sequence</tt></a>, and other objects which make usage of the

1342

local <tt class="docutils literal">schema</tt> name.</li>

1343

</ul>

1344

</td>

1345

</tr>

1346

</tbody>

1347

</table>

1348

1349

New in version 0.7.4: <tt class="docutils literal">schema</tt> and <tt class="docutils literal">quote_schema</tt> parameters.

1350

</div>

1351

</dd></dl>

1352

1353

1354

1355

<tt class="descname">append_ddl_listener</tt><big>(</big>event_name, listener<big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.append_ddl_listener" title="Permalink to this definition">¶</a></dt>

1356

<dd>Append a DDL event listener to this <tt class="docutils literal">MetaData</tt>.

1357

Deprecated. See <a class="reference internal" href="events.html#sqlalchemy.events.DDLEvents" title="sqlalchemy.events.DDLEvents"><tt class="xref py py-class docutils literal">DDLEvents</tt></a>.

1358

</dd></dl>

1359

1360

1361

1362

1363

<dd>An <a class="reference internal" href="connections.html#sqlalchemy.engine.Engine" title="sqlalchemy.engine.Engine"><tt class="xref py py-class docutils literal">Engine</tt></a> or <a class="reference internal" href="connections.html#sqlalchemy.engine.Connection" title="sqlalchemy.engine.Connection"><tt class="xref py py-class docutils literal">Connection</tt></a> to which this

1364

<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> is bound.

1365

Typically, a <a class="reference internal" href="connections.html#sqlalchemy.engine.Engine" title="sqlalchemy.engine.Engine"><tt class="xref py py-class docutils literal">Engine</tt></a> is assigned to this attribute

1366

so that “implicit execution” may be used, or alternatively

1367

as a means of providing engine binding information to an

1368

ORM <a class="reference internal" href="../orm/session.html#sqlalchemy.orm.session.Session" title="sqlalchemy.orm.session.Session"><tt class="xref py py-class docutils literal">Session</tt></a> object:

1369

<div class="highlight-python"><div class="highlight"><pre>engine = create_engine("someurl://")

1370

metadata.bind = engine</pre></div>

1371

</div>

1372

1373

See also

1374

<a class="reference internal" href="connections.html#dbengine-implicit">Connectionless Execution, Implicit Execution</a> - background on “bound metadata”

1375

</div>

1376

</dd></dl>

1377

1378

1379

1380

<tt class="descname">clear</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.clear" title="Permalink to this definition">¶</a></dt>

1381

<dd>Clear all Table objects from this MetaData.

1382

</dd></dl>

1383

1384

1385

1386

<tt class="descname">create_all</tt><big>(</big>bind=None, tables=None, checkfirst=True<big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.create_all" title="Permalink to this definition">¶</a></dt>

1387

<dd>Create all tables stored in this metadata.

1388

Conditional by default, will not attempt to recreate tables already

1389

present in the target database.

1390

1391

1392

1393

1394

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1395

<li>bind – A <a class="reference internal" href="connections.html#sqlalchemy.engine.Connectable" title="sqlalchemy.engine.Connectable"><tt class="xref py py-class docutils literal">Connectable</tt></a> used to access the

1396

database; if None, uses the existing bind on this <tt class="docutils literal">MetaData</tt>, if

1397

any.</li>

1398

<li>tables – Optional list of <tt class="docutils literal">Table</tt> objects, which is a subset of the total

1399

tables in the <tt class="docutils literal">MetaData</tt> (others are ignored).</li>

1400

<li>checkfirst – Defaults to True, don’t issue CREATEs for tables already present

1401

in the target database.</li>

1402

</ul>

1403

</td>

1404

</tr>

1405

</tbody>

1406

</table>

1407

</dd></dl>

1408

1409

1410

1411

<tt class="descname">drop_all</tt><big>(</big>bind=None, tables=None, checkfirst=True<big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.drop_all" title="Permalink to this definition">¶</a></dt>

1412

<dd>Drop all tables stored in this metadata.

1413

Conditional by default, will not attempt to drop tables not present in

1414

the target database.

1415

1416

1417

1418

1419

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1420

<li>bind – A <a class="reference internal" href="connections.html#sqlalchemy.engine.Connectable" title="sqlalchemy.engine.Connectable"><tt class="xref py py-class docutils literal">Connectable</tt></a> used to access the

1421

database; if None, uses the existing bind on this <tt class="docutils literal">MetaData</tt>, if

1422

any.</li>

1423

<li>tables – Optional list of <tt class="docutils literal">Table</tt> objects, which is a subset of the

1424

total tables in the <tt class="docutils literal">MetaData</tt> (others are ignored).</li>

1425

<li>checkfirst – Defaults to True, only issue DROPs for tables confirmed to be

1426

present in the target database.</li>

1427

</ul>

1428

</td>

1429

</tr>

1430

</tbody>

1431

</table>

1432

</dd></dl>

1433

1434

1435

1436

<tt class="descname">is_bound</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.is_bound" title="Permalink to this definition">¶</a></dt>

1437

<dd>True if this MetaData is bound to an Engine or Connection.

1438

</dd></dl>

1439

1440

1441

1442

<tt class="descname">reflect</tt><big>(</big>bind=None, schema=None, views=False, only=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.reflect" title="Permalink to this definition">¶</a></dt>

1443

<dd>Load all available table definitions from the database.

1444

Automatically creates <tt class="docutils literal">Table</tt> entries in this <tt class="docutils literal">MetaData</tt> for any

1445

table available in the database but not yet present in the

1446

<tt class="docutils literal">MetaData</tt>. May be called multiple times to pick up tables recently

1447

added to the database, however no special action is taken if a table

1448

in this <tt class="docutils literal">MetaData</tt> no longer exists in the database.

1449

1450

1451

1452

1453

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1454

<li>bind – A <a class="reference internal" href="connections.html#sqlalchemy.engine.Connectable" title="sqlalchemy.engine.Connectable"><tt class="xref py py-class docutils literal">Connectable</tt></a> used to access the database; if None, uses

1455

the existing bind on this <tt class="docutils literal">MetaData</tt>, if any.</li>

1456

<li>schema – Optional, query and reflect tables from an alterate schema.

1457

If None, the schema associated with this <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>

1458

is used, if any.</li>

1459

<li>views – If True, also reflect views.</li>

1460

<li>only – Optional. Load only a sub-set of available named tables. May be

1461

specified as a sequence of names or a callable.

1462

If a sequence of names is provided, only those tables will be

1463

reflected. An error is raised if a table is requested but not

1464

available. Named tables already present in this <tt class="docutils literal">MetaData</tt> are

1465

ignored.

1466

If a callable is provided, it will be used as a boolean predicate to

1467

filter the list of potential table names. The callable is called

1468

with a table name and this <tt class="docutils literal">MetaData</tt> instance as positional

1469

arguments and should return a true value for any table to reflect.

1470

</li>

1471

</ul>

1472

</td>

1473

</tr>

1474

</tbody>

1475

</table>

1476

</dd></dl>

1477

1478

1479

1480

<tt class="descname">remove</tt><big>(</big>table<big>)</big><a class="headerlink" href="#sqlalchemy.schema.MetaData.remove" title="Permalink to this definition">¶</a></dt>

1481

<dd>Remove the given Table object from this MetaData.

1482

</dd></dl>

1483

1484

1485

1486

<tt class="descname">sorted_tables</tt><a class="headerlink" href="#sqlalchemy.schema.MetaData.sorted_tables" title="Permalink to this definition">¶</a></dt>

1487

<dd>Returns a list of <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects sorted in order of

1488

foreign key dependency.

1489

The sorting will place <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> objects that have dependencies

1490

first, before the dependencies themselves, representing the

1491

order in which they can be created. To get the order in which

1492

the tables would be dropped, use the <tt class="docutils literal">reversed()</tt> Python built-in.

1493

1494

See also

1495

<tt class="xref py py-meth docutils literal">Inspector.sorted_tables()</tt>

1496

</div>

1497

</dd></dl>

1498

1499

</dd></dl>

1500

1501

1502

1503

class <tt class="descclassname">sqlalchemy.schema.</tt><tt class="descname">SchemaItem</tt><a class="headerlink" href="#sqlalchemy.schema.SchemaItem" title="Permalink to this definition">¶</a></dt>

1504

<dd>Bases: <a class="reference internal" href="events.html#sqlalchemy.events.SchemaEventTarget" title="sqlalchemy.events.SchemaEventTarget"><tt class="xref py py-class docutils literal">sqlalchemy.events.SchemaEventTarget</tt></a>, <tt class="xref py py-class docutils literal">sqlalchemy.sql.visitors.Visitable</tt>

1505

Base class for items that define a database schema.

1506

1507

1508

<tt class="descname">get_children</tt><big>(</big>**kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.SchemaItem.get_children" title="Permalink to this definition">¶</a></dt>

1509

<dd>used to allow SchemaVisitor access

1510

</dd></dl>

1511

1512

1513

1514

1515

<dd>Info dictionary associated with the object, allowing user-defined

1516

data to be associated with this <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">SchemaItem</tt></a>.

1517

The dictionary is automatically generated when first accessed.

1518

It can also be specified in the constructor of some objects,

1519

such as <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> and <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a>.

1520

</dd></dl>

1521

1522

</dd></dl>

1523

1524

1525

1526

class <tt class="descclassname">sqlalchemy.schema.</tt><tt class="descname">Table</tt><big>(</big>*args, **kw<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table" title="Permalink to this definition">¶</a></dt>

1527

<dd>Bases: <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">sqlalchemy.schema.SchemaItem</tt></a>, <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">sqlalchemy.sql.expression.TableClause</tt></a>

1528

Represent a table in a database.

1529

e.g.:

1530

<div class="highlight-python"><div class="highlight"><pre>mytable = Table("mytable", metadata,

1531

Column('mytable_id', Integer, primary_key=True),

1532

Column('value', String(50))

1533

)</pre></div>

1534

</div>

1535

The <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> object constructs a unique instance of itself based

1536

on its name and optional schema name within the given

1537

<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> object. Calling the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>

1538

constructor with the same name and same <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> argument

1539

a second time will return the same <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> object - in this way

1540

the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> constructor acts as a registry function.

1541

1542

See also

1543

<a class="reference internal" href="#metadata-describing">Describing Databases with MetaData</a> - Introduction to database metadata

1544

</div>

1545

Constructor arguments are as follows:

1546

1547

1548

1549

1550

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1551

<li>name – The name of this table as represented in the database.

1552

This property, along with the schema, indicates the singleton

1553

identity of this table in relation to its parent <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>.

1554

Additional calls to <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> with the same name, metadata,

1555

and schema name will return the same <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> object.

1556

Names which contain no upper case characters

1557

will be treated as case insensitive names, and will not be quoted

1558

unless they are a reserved word. Names with any number of upper

1559

case characters will be quoted and sent exactly. Note that this

1560

behavior applies even for databases which standardize upper

1561

case names as case insensitive such as Oracle.

1562

</li>

1563

<li>metadata – a <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> object which will contain this

1564

table. The metadata is used as a point of association of this table

1565

with other tables which are referenced via foreign key. It also

1566

may be used to associate this table with a particular

1567

<a class="reference internal" href="connections.html#sqlalchemy.engine.Connectable" title="sqlalchemy.engine.Connectable"><tt class="xref py py-class docutils literal">Connectable</tt></a>.</li>

1568

<li>*args – Additional positional arguments are used primarily

1569

to add the list of <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a> objects contained within this

1570

table. Similar to the style of a CREATE TABLE statement, other

1571

<a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">SchemaItem</tt></a> constructs may be added here, including

1572

<a class="reference internal" href="constraints.html#sqlalchemy.schema.PrimaryKeyConstraint" title="sqlalchemy.schema.PrimaryKeyConstraint"><tt class="xref py py-class docutils literal">PrimaryKeyConstraint</tt></a>, and <a class="reference internal" href="constraints.html#sqlalchemy.schema.ForeignKeyConstraint" title="sqlalchemy.schema.ForeignKeyConstraint"><tt class="xref py py-class docutils literal">ForeignKeyConstraint</tt></a>.</li>

1573

<li>autoload – Defaults to False: the Columns for this table should

1574

be reflected from the database. Usually there will be no Column

1575

objects in the constructor if this property is set.</li>

1576

<li>autoload_replace – If <tt class="docutils literal">True</tt>, when using <tt class="docutils literal">autoload=True</tt>

1577

and <tt class="docutils literal">extend_existing=True</tt>,

1578

replace <tt class="docutils literal">Column</tt> objects already present in the <tt class="docutils literal">Table</tt> that’s

1579

in the <tt class="docutils literal">MetaData</tt> registry with

1580

what’s reflected. Otherwise, all existing columns will be

1581

excluded from the reflection process. Note that this does

1582

not impact <tt class="docutils literal">Column</tt> objects specified in the same call to <tt class="docutils literal">Table</tt>

1583

which includes <tt class="docutils literal">autoload</tt>, those always take precedence.

1584

Defaults to <tt class="docutils literal">True</tt>.

1585

1586

New in version 0.7.5.

1587

</div>

1588

</li>

1589

<li>autoload_with – If autoload==True, this is an optional Engine

1590

or Connection instance to be used for the table reflection. If

1591

<tt class="docutils literal">None</tt>, the underlying MetaData’s bound connectable will be used.</li>

1592

<li>extend_existing – When <tt class="docutils literal">True</tt>, indicates that if this

1593

<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> is already present in the given <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>,

1594

apply further arguments within the constructor to the existing

1595

<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>.

1596

If <tt class="docutils literal">extend_existing</tt> or <tt class="docutils literal">keep_existing</tt> are not set, an error is

1597

raised if additional table modifiers are specified when

1598

the given <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> is already present in the <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>.

1599

1600

Changed in version 0.7.4: <tt class="docutils literal">extend_existing</tt> will work in conjunction

1601

with <tt class="docutils literal">autoload=True</tt> to run a new reflection operation against

1602

the database; new <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a> objects will be produced

1603

from database metadata to replace those existing with the same

1604

name, and additional <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a> objects not present

1605

in the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> will be added.

1606

</div>

1607

As is always the case with <tt class="docutils literal">autoload=True</tt>, <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a>

1608

objects can be specified in the same <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> constructor,

1609

which will take precedence. I.e.:

1610

<div class="highlight-python"><div class="highlight"><pre>Table("mytable", metadata,

1611

Column('y', Integer),

1612

extend_existing=True,

1613

autoload=True,

1614

autoload_with=engine

1615

)</pre></div>

1616

</div>

1617

The above will overwrite all columns within <tt class="docutils literal">mytable</tt> which

1618

are present in the database, except for <tt class="docutils literal">y</tt> which will be used as is

1619

from the above definition. If the <tt class="docutils literal">autoload_replace</tt> flag

1620

is set to False, no existing columns will be replaced.

1621

</li>

1622

<li>implicit_returning – True by default - indicates that

1623

RETURNING can be used by default to fetch newly inserted primary key

1624

values, for backends which support this. Note that

1625

create_engine() also provides an implicit_returning flag.</li>

1626

<li>include_columns – A list of strings indicating a subset of

1627

columns to be loaded via the <tt class="docutils literal">autoload</tt> operation; table columns who

1628

aren’t present in this list will not be represented on the resulting

1629

<tt class="docutils literal">Table</tt> object. Defaults to <tt class="docutils literal">None</tt> which indicates all columns

1630

should be reflected.</li>

1631

<li>info – Optional data dictionary which will be populated into the

1632

<a class="reference internal" href="#sqlalchemy.schema.SchemaItem.info" title="sqlalchemy.schema.SchemaItem.info"><tt class="xref py py-attr docutils literal">SchemaItem.info</tt></a> attribute of this object.</li>

1633

<li>keep_existing – When <tt class="docutils literal">True</tt>, indicates that if this Table

1634

is already present in the given <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>, ignore

1635

further arguments within the constructor to the existing

1636

<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>, and return the <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> object as

1637

originally created. This is to allow a function that wishes

1638

to define a new <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> on first call, but on

1639

subsequent calls will return the same <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>,

1640

without any of the declarations (particularly constraints)

1641

being applied a second time. Also see extend_existing.

1642

If extend_existing or keep_existing are not set, an error is

1643

raised if additional table modifiers are specified when

1644

the given <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> is already present in the <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>.

1645

</li>

1646

<li>listeners – A list of tuples of the form <tt class="docutils literal">(<eventname>, <fn>)</tt>

1647

which will be passed to <a class="reference internal" href="event.html#sqlalchemy.event.listen" title="sqlalchemy.event.listen"><tt class="xref py py-func docutils literal">event.listen()</tt></a> upon construction.

1648

This alternate hook to <a class="reference internal" href="event.html#sqlalchemy.event.listen" title="sqlalchemy.event.listen"><tt class="xref py py-func docutils literal">event.listen()</tt></a> allows the establishment

1649

of a listener function specific to this <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> before

1650

the “autoload” process begins. Particularly useful for

1651

the <a class="reference internal" href="events.html#sqlalchemy.events.DDLEvents.column_reflect" title="sqlalchemy.events.DDLEvents.column_reflect"><tt class="xref py py-meth docutils literal">DDLEvents.column_reflect()</tt></a> event:

1652

<div class="highlight-python"><div class="highlight"><pre>def listen_for_reflect(table, column_info):

1653

"handle the column reflection event"

1654

# ...

1655

1656

t = Table(

1657

'sometable',

1658

autoload=True,

1659

listeners=[

1660

('column_reflect', listen_for_reflect)

1661

])</pre></div>

1662

</div>

1663

</li>

1664

<li>mustexist – When <tt class="docutils literal">True</tt>, indicates that this Table must already

1665

be present in the given <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> collection, else

1666

an exception is raised.</li>

1667

<li>prefixes – A list of strings to insert after CREATE in the CREATE TABLE

1668

statement. They will be separated by spaces.</li>

1669

<li>quote – Force quoting of this table’s name on or off, corresponding

1670

to <tt class="docutils literal">True</tt> or <tt class="docutils literal">False</tt>. When left at its default of <tt class="docutils literal">None</tt>,

1671

the column identifier will be quoted according to whether the name is

1672

case sensitive (identifiers with at least one upper case character are

1673

treated as case sensitive), or if it’s a reserved word. This flag

1674

is only needed to force quoting of a reserved word which is not known

1675

by the SQLAlchemy dialect.</li>

1676

<li>quote_schema – same as ‘quote’ but applies to the schema identifier.</li>

1677

<li>schema – The schema name for this table, which is required if

1678

the table resides in a schema other than the default selected schema

1679

for the engine’s database connection. Defaults to <tt class="docutils literal">None</tt>.</li>

1680

<li>useexisting – Deprecated. Use extend_existing.</li>

1681

</ul>

1682

</td>

1683

</tr>

1684

</tbody>

1685

</table>

1686

1687

1688

1689

<dd>Constructor for <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>.

1690

This method is a no-op. See the top-level

1691

documentation for <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>

1692

for constructor arguments.

1693

</dd></dl>

1694

1695

1696

1697

<tt class="descname">add_is_dependent_on</tt><big>(</big>table<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.add_is_dependent_on" title="Permalink to this definition">¶</a></dt>

1698

<dd>Add a ‘dependency’ for this Table.

1699

This is another Table object which must be created

1700

first before this one can, or dropped after this one.

1701

Usually, dependencies between tables are determined via

1702

ForeignKey objects. However, for other situations that

1703

create dependencies outside of foreign keys (rules, inheriting),

1704

this method can manually establish such a link.

1705

</dd></dl>

1706

1707

1708

1709

<tt class="descname">alias</tt><big>(</big>name=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.alias" title="Permalink to this definition">¶</a></dt>

1710

1711

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.alias" title="sqlalchemy.sql.expression.FromClause.alias"><tt class="xref py py-meth docutils literal">alias()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

1712

return an alias of this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>.

1713

This is shorthand for calling:

1714

<div class="highlight-python"><div class="highlight"><pre>from sqlalchemy import alias

1715

a = alias(self, name=name)</pre></div>

1716

</div>

1717

See <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.alias" title="sqlalchemy.sql.expression.alias"><tt class="xref py py-func docutils literal">alias()</tt></a> for details.

1718

</dd></dl>

1719

1720

1721

1722

<tt class="descname">append_column</tt><big>(</big>column<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.append_column" title="Permalink to this definition">¶</a></dt>

1723

<dd>Append a <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a> to this <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>.

1724

The “key” of the newly added <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a>, i.e. the

1725

value of its <tt class="docutils literal">.key</tt> attribute, will then be available

1726

in the <tt class="docutils literal">.c</tt> collection of this <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>, and the

1727

column definition will be included in any CREATE TABLE, SELECT,

1728

UPDATE, etc. statements generated from this <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>

1729

construct.

1730

Note that this does not change the definition of the table

1731

as it exists within any underlying database, assuming that

1732

table has already been created in the database. Relational

1733

databases support the addition of columns to existing tables

1734

using the SQL ALTER command, which would need to be

1735

emitted for an already-existing table that doesn’t contain

1736

the newly added column.

1737

</dd></dl>

1738

1739

1740

1741

<tt class="descname">append_constraint</tt><big>(</big>constraint<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.append_constraint" title="Permalink to this definition">¶</a></dt>

1742

<dd>Append a <a class="reference internal" href="constraints.html#sqlalchemy.schema.Constraint" title="sqlalchemy.schema.Constraint"><tt class="xref py py-class docutils literal">Constraint</tt></a> to this

1743

<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>.

1744

This has the effect of the constraint being included in any

1745

future CREATE TABLE statement, assuming specific DDL creation

1746

events have not been associated with the given

1747

<a class="reference internal" href="constraints.html#sqlalchemy.schema.Constraint" title="sqlalchemy.schema.Constraint"><tt class="xref py py-class docutils literal">Constraint</tt></a> object.

1748

Note that this does not produce the constraint within the

1749

relational database automatically, for a table that already exists

1750

in the database. To add a constraint to an

1751

existing relational database table, the SQL ALTER command must

1752

be used. SQLAlchemy also provides the

1753

<a class="reference internal" href="ddl.html#sqlalchemy.schema.AddConstraint" title="sqlalchemy.schema.AddConstraint"><tt class="xref py py-class docutils literal">AddConstraint</tt></a> construct which can produce this SQL when

1754

invoked as an executable clause.

1755

</dd></dl>

1756

1757

1758

1759

<tt class="descname">append_ddl_listener</tt><big>(</big>event_name, listener<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.append_ddl_listener" title="Permalink to this definition">¶</a></dt>

1760

<dd>Append a DDL event listener to this <tt class="docutils literal">Table</tt>.

1761

Deprecated. See <a class="reference internal" href="events.html#sqlalchemy.events.DDLEvents" title="sqlalchemy.events.DDLEvents"><tt class="xref py py-class docutils literal">DDLEvents</tt></a>.

1762

</dd></dl>

1763

1764

1765

1766

1767

<dd>Return the connectable associated with this Table.

1768

</dd></dl>

1769

1770

1771

1772

1773

1774

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.c" title="sqlalchemy.sql.expression.FromClause.c"><tt class="xref py py-attr docutils literal">c</tt></a> attribute of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

1775

An alias for the <a class="reference internal" href="#sqlalchemy.schema.Table.columns" title="sqlalchemy.schema.Table.columns"><tt class="xref py py-attr docutils literal">columns</tt></a> attribute.

1776

</dd></dl>

1777

1778

1779

1780

<tt class="descname">columns</tt><a class="headerlink" href="#sqlalchemy.schema.Table.columns" title="Permalink to this definition">¶</a></dt>

1781

1782

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.columns" title="sqlalchemy.sql.expression.FromClause.columns"><tt class="xref py py-attr docutils literal">columns</tt></a> attribute of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

1783

A named-based collection of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a> objects

1784

maintained by this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>.

1785

The <a class="reference internal" href="#sqlalchemy.schema.Table.columns" title="sqlalchemy.schema.Table.columns"><tt class="xref py py-attr docutils literal">columns</tt></a>, or <a class="reference internal" href="#sqlalchemy.schema.Table.c" title="sqlalchemy.schema.Table.c"><tt class="xref py py-attr docutils literal">c</tt></a> collection, is the gateway

1786

to the construction of SQL expressions using table-bound or

1787

other selectable-bound columns:

1788

<div class="highlight-python"><div class="highlight"><pre>select([mytable]).where(mytable.c.somecolumn == 5)</pre></div>

1789

</div>

1790

</dd></dl>

1791

1792

1793

1794

<tt class="descname">compare</tt><big>(</big>other, **kw<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.compare" title="Permalink to this definition">¶</a></dt>

1795

1796

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement.compare" title="sqlalchemy.sql.expression.ClauseElement.compare"><tt class="xref py py-meth docutils literal">compare()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a></div>

1797

Compare this ClauseElement to the given ClauseElement.

1798

Subclasses should override the default behavior, which is a

1799

straight identity comparison.

1800

**kw are arguments consumed by subclass compare() methods and

1801

may be used to modify the criteria for comparison.

1802

(see <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a>)

1803

</dd></dl>

1804

1805

1806

1807

<tt class="descname">compile</tt><big>(</big>bind=None, dialect=None, **kw<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.compile" title="Permalink to this definition">¶</a></dt>

1808

1809

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement.compile" title="sqlalchemy.sql.expression.ClauseElement.compile"><tt class="xref py py-meth docutils literal">compile()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a></div>

1810

Compile this SQL expression.

1811

The return value is a <a class="reference internal" href="internals.html#sqlalchemy.engine.interfaces.Compiled" title="sqlalchemy.engine.interfaces.Compiled"><tt class="xref py py-class docutils literal">Compiled</tt></a> object.

1812

Calling <tt class="docutils literal">str()</tt> or <tt class="docutils literal">unicode()</tt> on the returned value will yield a

1813

string representation of the result. The

1814

<a class="reference internal" href="internals.html#sqlalchemy.engine.interfaces.Compiled" title="sqlalchemy.engine.interfaces.Compiled"><tt class="xref py py-class docutils literal">Compiled</tt></a> object also can return a

1815

dictionary of bind parameter names and values

1816

using the <tt class="docutils literal">params</tt> accessor.

1817

1818

1819

1820

1821

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1822

<li>bind – An <tt class="docutils literal">Engine</tt> or <tt class="docutils literal">Connection</tt> from which a

1823

<tt class="docutils literal">Compiled</tt> will be acquired. This argument takes precedence over

1824

this <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>‘s bound engine, if any.</li>

1825

<li>column_keys – Used for INSERT and UPDATE statements, a list of

1826

column names which should be present in the VALUES clause of the

1827

compiled statement. If <tt class="docutils literal">None</tt>, all columns from the target table

1828

object are rendered.</li>

1829

<li>dialect – A <tt class="docutils literal">Dialect</tt> instance from which a <tt class="docutils literal">Compiled</tt>

1830

will be acquired. This argument takes precedence over the <cite>bind</cite>

1831

argument as well as this <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>‘s bound engine, if

1832

any.</li>

1833

<li>inline – Used for INSERT statements, for a dialect which does

1834

not support inline retrieval of newly generated primary key

1835

columns, will force the expression used to create the new primary

1836

key value to be rendered inline within the INSERT statement’s

1837

VALUES clause. This typically refers to Sequence execution but may

1838

also refer to any server-side default generation function

1839

associated with a primary key <cite>Column</cite>.</li>

1840

</ul>

1841

</td>

1842

</tr>

1843

</tbody>

1844

</table>

1845

</dd></dl>

1846

1847

1848

1849

<tt class="descname">correspond_on_equivalents</tt><big>(</big>column, equivalents<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.correspond_on_equivalents" title="Permalink to this definition">¶</a></dt>

1850

1851

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.correspond_on_equivalents" title="sqlalchemy.sql.expression.FromClause.correspond_on_equivalents"><tt class="xref py py-meth docutils literal">correspond_on_equivalents()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

1852

Return corresponding_column for the given column, or if None

1853

search for a match in the given dictionary.

1854

</dd></dl>

1855

1856

1857

1858

<tt class="descname">corresponding_column</tt><big>(</big>column, require_embedded=False<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.corresponding_column" title="Permalink to this definition">¶</a></dt>

1859

1860

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.corresponding_column" title="sqlalchemy.sql.expression.FromClause.corresponding_column"><tt class="xref py py-meth docutils literal">corresponding_column()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

1861

Given a <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a>, return the exported

1862

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a> object from this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.Selectable" title="sqlalchemy.sql.expression.Selectable"><tt class="xref py py-class docutils literal">Selectable</tt></a>

1863

which corresponds to that original

1864

<a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a> via a common ancestor

1865

column.

1866

1867

1868

1869

1870

<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

1871

<li>column – the target <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a> to be matched</li>

1872

<li>require_embedded – only return corresponding columns for</li>

1873

</ul>

1874

</td>

1875

</tr>

1876

</tbody>

1877

</table>

1878

the given <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a>, if the given

1879

<a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ColumnElement" title="sqlalchemy.sql.expression.ColumnElement"><tt class="xref py py-class docutils literal">ColumnElement</tt></a> is actually present within a sub-element

1880

of this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>. Normally the column will match if

1881

it merely shares a common ancestor with one of the exported

1882

columns of this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>.

1883

</dd></dl>

1884

1885

1886

1887

<tt class="descname">count</tt><big>(</big>whereclause=None, **params<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.count" title="Permalink to this definition">¶</a></dt>

1888

1889

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause.count" title="sqlalchemy.sql.expression.TableClause.count"><tt class="xref py py-meth docutils literal">count()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a></div>

1890

return a SELECT COUNT generated against this

1891

<a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a>.

1892

</dd></dl>

1893

1894

1895

1896

<tt class="descname">create</tt><big>(</big>bind=None, checkfirst=False<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.create" title="Permalink to this definition">¶</a></dt>

1897

<dd>Issue a <tt class="docutils literal">CREATE</tt> statement for this

1898

<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>, using the given <a class="reference internal" href="connections.html#sqlalchemy.engine.Connectable" title="sqlalchemy.engine.Connectable"><tt class="xref py py-class docutils literal">Connectable</tt></a>

1899

for connectivity.

1900

1901

See also

1902

<a class="reference internal" href="#sqlalchemy.schema.MetaData.create_all" title="sqlalchemy.schema.MetaData.create_all"><tt class="xref py py-meth docutils literal">MetaData.create_all()</tt></a>.

1903

</div>

1904

</dd></dl>

1905

1906

1907

1908

<tt class="descname">delete</tt><big>(</big>whereclause=None, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.delete" title="Permalink to this definition">¶</a></dt>

1909

1910

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause.delete" title="sqlalchemy.sql.expression.TableClause.delete"><tt class="xref py py-meth docutils literal">delete()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a></div>

1911

Generate a <a class="reference internal" href="dml.html#sqlalchemy.sql.expression.delete" title="sqlalchemy.sql.expression.delete"><tt class="xref py py-func docutils literal">delete()</tt></a> construct against this

1912

<a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a>.

1913

E.g.:

1914

<div class="highlight-python"><div class="highlight"><pre>table.delete().where(table.c.id==7)</pre></div>

1915

</div>

1916

See <a class="reference internal" href="dml.html#sqlalchemy.sql.expression.delete" title="sqlalchemy.sql.expression.delete"><tt class="xref py py-func docutils literal">delete()</tt></a> for argument and usage information.

1917

</dd></dl>

1918

1919

1920

1921

<tt class="descname">description</tt><a class="headerlink" href="#sqlalchemy.schema.Table.description" title="Permalink to this definition">¶</a></dt>

1922

1923

inherited from the <tt class="xref py py-attr docutils literal">description</tt> attribute of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a></div>

1924

</dd></dl>

1925

1926

1927

1928

<tt class="descname">dispatch</tt><a class="headerlink" href="#sqlalchemy.schema.Table.dispatch" title="Permalink to this definition">¶</a></dt>

1929

<dd>alias of <tt class="xref py py-class docutils literal">DDLEventsDispatch</tt>

1930

</dd></dl>

1931

1932

1933

1934

<tt class="descname">drop</tt><big>(</big>bind=None, checkfirst=False<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.drop" title="Permalink to this definition">¶</a></dt>

1935

<dd>Issue a <tt class="docutils literal">DROP</tt> statement for this

1936

<a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>, using the given <a class="reference internal" href="connections.html#sqlalchemy.engine.Connectable" title="sqlalchemy.engine.Connectable"><tt class="xref py py-class docutils literal">Connectable</tt></a>

1937

for connectivity.

1938

1939

See also

1940

<a class="reference internal" href="#sqlalchemy.schema.MetaData.drop_all" title="sqlalchemy.schema.MetaData.drop_all"><tt class="xref py py-meth docutils literal">MetaData.drop_all()</tt></a>.

1941

</div>

1942

</dd></dl>

1943

1944

1945

1946

<tt class="descname">exists</tt><big>(</big>bind=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.exists" title="Permalink to this definition">¶</a></dt>

1947

<dd>Return True if this table exists.

1948

</dd></dl>

1949

1950

1951

1952

<tt class="descname">foreign_keys</tt><a class="headerlink" href="#sqlalchemy.schema.Table.foreign_keys" title="Permalink to this definition">¶</a></dt>

1953

1954

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.foreign_keys" title="sqlalchemy.sql.expression.FromClause.foreign_keys"><tt class="xref py py-attr docutils literal">foreign_keys</tt></a> attribute of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

1955

Return the collection of ForeignKey objects which this

1956

FromClause references.

1957

</dd></dl>

1958

1959

1960

1961

<tt class="descname">get_children</tt><big>(</big>column_collections=True, schema_visitor=False, **kw<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.get_children" title="Permalink to this definition">¶</a></dt>

1962

1963

1964

1965

1966

<tt class="descname">implicit_returning</tt> = False<a class="headerlink" href="#sqlalchemy.schema.Table.implicit_returning" title="Permalink to this definition">¶</a></dt>

1967

1968

1969

1970

1971

1972

1973

inherited from the <a class="reference internal" href="#sqlalchemy.schema.SchemaItem.info" title="sqlalchemy.schema.SchemaItem.info"><tt class="xref py py-attr docutils literal">info</tt></a> attribute of <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">SchemaItem</tt></a></div>

1974

Info dictionary associated with the object, allowing user-defined

1975

data to be associated with this <a class="reference internal" href="#sqlalchemy.schema.SchemaItem" title="sqlalchemy.schema.SchemaItem"><tt class="xref py py-class docutils literal">SchemaItem</tt></a>.

1976

The dictionary is automatically generated when first accessed.

1977

It can also be specified in the constructor of some objects,

1978

such as <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> and <a class="reference internal" href="#sqlalchemy.schema.Column" title="sqlalchemy.schema.Column"><tt class="xref py py-class docutils literal">Column</tt></a>.

1979

</dd></dl>

1980

1981

1982

1983

<tt class="descname">insert</tt><big>(</big>values=None, inline=False, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.insert" title="Permalink to this definition">¶</a></dt>

1984

1985

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause.insert" title="sqlalchemy.sql.expression.TableClause.insert"><tt class="xref py py-meth docutils literal">insert()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a></div>

1986

Generate an <a class="reference internal" href="dml.html#sqlalchemy.sql.expression.insert" title="sqlalchemy.sql.expression.insert"><tt class="xref py py-func docutils literal">insert()</tt></a> construct against this

1987

<a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a>.

1988

E.g.:

1989

<div class="highlight-python"><div class="highlight"><pre>table.insert().values(name='foo')</pre></div>

1990

</div>

1991

See <a class="reference internal" href="dml.html#sqlalchemy.sql.expression.insert" title="sqlalchemy.sql.expression.insert"><tt class="xref py py-func docutils literal">insert()</tt></a> for argument and usage information.

1992

</dd></dl>

1993

1994

1995

1996

<tt class="descname">is_clause_element</tt> = True<a class="headerlink" href="#sqlalchemy.schema.Table.is_clause_element" title="Permalink to this definition">¶</a></dt>

1997

1998

1999

2000

2001

<tt class="descname">is_derived_from</tt><big>(</big>fromclause<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.is_derived_from" title="Permalink to this definition">¶</a></dt>

2002

2003

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.is_derived_from" title="sqlalchemy.sql.expression.FromClause.is_derived_from"><tt class="xref py py-meth docutils literal">is_derived_from()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

2004

Return True if this FromClause is ‘derived’ from the given

2005

FromClause.

2006

An example would be an Alias of a Table is derived from that Table.

2007

</dd></dl>

2008

2009

2010

2011

<tt class="descname">is_selectable</tt> = True<a class="headerlink" href="#sqlalchemy.schema.Table.is_selectable" title="Permalink to this definition">¶</a></dt>

2012

2013

2014

2015

2016

<tt class="descname">join</tt><big>(</big>right, onclause=None, isouter=False<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.join" title="Permalink to this definition">¶</a></dt>

2017

2018

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.join" title="sqlalchemy.sql.expression.FromClause.join"><tt class="xref py py-meth docutils literal">join()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

2019

return a join of this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a> against another

2020

<a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>.

2021

</dd></dl>

2022

2023

2024

2025

2026

2027

2028

2029

2030

<tt class="descname">named_with_column</tt> = True<a class="headerlink" href="#sqlalchemy.schema.Table.named_with_column" title="Permalink to this definition">¶</a></dt>

2031

2032

2033

2034

2035

<tt class="descname">outerjoin</tt><big>(</big>right, onclause=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.outerjoin" title="Permalink to this definition">¶</a></dt>

2036

2037

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.outerjoin" title="sqlalchemy.sql.expression.FromClause.outerjoin"><tt class="xref py py-meth docutils literal">outerjoin()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

2038

return an outer join of this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a> against another

2039

<a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>.

2040

</dd></dl>

2041

2042

2043

2044

<tt class="descname">params</tt><big>(</big>*optionaldict, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.params" title="Permalink to this definition">¶</a></dt>

2045

2046

inherited from the <tt class="xref py py-meth docutils literal">params()</tt> method of <tt class="xref py py-class docutils literal">Immutable</tt></div>

2047

</dd></dl>

2048

2049

2050

2051

<tt class="descname">primary_key</tt><a class="headerlink" href="#sqlalchemy.schema.Table.primary_key" title="Permalink to this definition">¶</a></dt>

2052

2053

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.primary_key" title="sqlalchemy.sql.expression.FromClause.primary_key"><tt class="xref py py-attr docutils literal">primary_key</tt></a> attribute of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

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Return the collection of Column objects which comprise the

2055

primary key of this FromClause.

2056

</dd></dl>

2057

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<tt class="descname">quote</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Table.quote" title="Permalink to this definition">¶</a></dt>

2061

2062

2063

2064

2065

<tt class="descname">replace_selectable</tt><big>(</big>old, alias<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.replace_selectable" title="Permalink to this definition">¶</a></dt>

2066

2067

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.replace_selectable" title="sqlalchemy.sql.expression.FromClause.replace_selectable"><tt class="xref py py-meth docutils literal">replace_selectable()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

2068

replace all occurrences of FromClause ‘old’ with the given Alias

2069

object, returning a copy of this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>.

2070

</dd></dl>

2071

2072

2073

2074

<tt class="descname">schema</tt> = None<a class="headerlink" href="#sqlalchemy.schema.Table.schema" title="Permalink to this definition">¶</a></dt>

2075

2076

2077

2078

2079

<tt class="descname">select</tt><big>(</big>whereclause=None, **params<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.select" title="Permalink to this definition">¶</a></dt>

2080

2081

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause.select" title="sqlalchemy.sql.expression.FromClause.select"><tt class="xref py py-meth docutils literal">select()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a></div>

2082

return a SELECT of this <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.FromClause" title="sqlalchemy.sql.expression.FromClause"><tt class="xref py py-class docutils literal">FromClause</tt></a>.

2083

2084

See also

2085

<a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><tt class="xref py py-func docutils literal">select()</tt></a> - general purpose

2086

method which allows for arbitrary column lists.

2087

</div>

2088

</dd></dl>

2089

2090

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<tt class="descname">selectable</tt><a class="headerlink" href="#sqlalchemy.schema.Table.selectable" title="Permalink to this definition">¶</a></dt>

2093

2094

inherited from the <tt class="xref py py-attr docutils literal">selectable</tt> attribute of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.Selectable" title="sqlalchemy.sql.expression.Selectable"><tt class="xref py py-class docutils literal">Selectable</tt></a></div>

2095

</dd></dl>

2096

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<tt class="descname">self_group</tt><big>(</big>against=None<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.self_group" title="Permalink to this definition">¶</a></dt>

2100

2101

inherited from the <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement.self_group" title="sqlalchemy.sql.expression.ClauseElement.self_group"><tt class="xref py py-meth docutils literal">self_group()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a></div>

2102

Apply a ‘grouping’ to this <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>.

2103

This method is overridden by subclasses to return a

2104

“grouping” construct, i.e. parenthesis. In particular

2105

it’s used by “binary” expressions to provide a grouping

2106

around themselves when placed into a larger expression,

2107

as well as by <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><tt class="xref py py-func docutils literal">select()</tt></a> constructs when placed into

2108

the FROM clause of another <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.select" title="sqlalchemy.sql.expression.select"><tt class="xref py py-func docutils literal">select()</tt></a>. (Note that

2109

subqueries should be normally created using the

2110

<tt class="xref py py-func docutils literal">Select.alias()</tt> method, as many platforms require

2111

nested SELECT statements to be named).

2112

As expressions are composed together, the application of

2113

<a class="reference internal" href="#sqlalchemy.schema.Table.self_group" title="sqlalchemy.schema.Table.self_group"><tt class="xref py py-meth docutils literal">self_group()</tt></a> is automatic - end-user code should never

2114

need to use this method directly. Note that SQLAlchemy’s

2115

clause constructs take operator precedence into account -

2116

so parenthesis might not be needed, for example, in

2117

an expression like <tt class="docutils literal">x OR (y AND z)</tt> - AND takes precedence

2118

over OR.

2119

The base <a class="reference internal" href="#sqlalchemy.schema.Table.self_group" title="sqlalchemy.schema.Table.self_group"><tt class="xref py py-meth docutils literal">self_group()</tt></a> method of <a class="reference internal" href="sqlelement.html#sqlalchemy.sql.expression.ClauseElement" title="sqlalchemy.sql.expression.ClauseElement"><tt class="xref py py-class docutils literal">ClauseElement</tt></a>

2120

just returns self.

2121

</dd></dl>

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<tt class="descname">supports_execution</tt> = False<a class="headerlink" href="#sqlalchemy.schema.Table.supports_execution" title="Permalink to this definition">¶</a></dt>

2126

2127

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<tt class="descname">tometadata</tt><big>(</big>metadata, schema=<symbol 'retain_schema><big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.tometadata" title="Permalink to this definition">¶</a></dt>

2131

<dd>Return a copy of this <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> associated with a different

2132

<a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a>.

2133

E.g.:

2134

<div class="highlight-python"><div class="highlight"><pre>some_engine = create_engine("sqlite:///some.db")

2135

2136

# create two metadata

2137

meta1 = MetaData()

2138

meta2 = MetaData()

2139

2140

# load 'users' from the sqlite engine

2141

users_table = Table('users', meta1, autoload=True,

2142

autoload_with=some_engine)

2143

2144

# create the same Table object for the plain metadata

2145

users_table_2 = users_table.tometadata(meta2)</pre></div>

2146

</div>

2147

2148

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<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

2152

<li>metadata – Target <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">MetaData</tt></a> object.</li>

2153

<li>schema – Optional string name of a target schema, or

2154

<tt class="docutils literal">None</tt> for no schema. The <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a> object will be

2155

given this schema name upon copy. Defaults to the special

2156

symbol <tt class="xref py py-attr docutils literal">RETAIN_SCHEMA</tt> which indicates no change should be

2157

made to the schema name of the resulting <a class="reference internal" href="#sqlalchemy.schema.Table" title="sqlalchemy.schema.Table"><tt class="xref py py-class docutils literal">Table</tt></a>.</li>

2158

</ul>

2159

</td>

2160

</tr>

2161

</tbody>

2162

</table>

2163

</dd></dl>

2164

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2167

<tt class="descname">unique_params</tt><big>(</big>*optionaldict, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.unique_params" title="Permalink to this definition">¶</a></dt>

2168

2169

inherited from the <tt class="xref py py-meth docutils literal">unique_params()</tt> method of <tt class="xref py py-class docutils literal">Immutable</tt></div>

2170

</dd></dl>

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<tt class="descname">update</tt><big>(</big>whereclause=None, values=None, inline=False, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.schema.Table.update" title="Permalink to this definition">¶</a></dt>

2175

2176

inherited from the <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause.update" title="sqlalchemy.sql.expression.TableClause.update"><tt class="xref py py-meth docutils literal">update()</tt></a> method of <a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a></div>

2177

Generate an <a class="reference internal" href="dml.html#sqlalchemy.sql.expression.update" title="sqlalchemy.sql.expression.update"><tt class="xref py py-func docutils literal">update()</tt></a> construct against this

2178

<a class="reference internal" href="selectable.html#sqlalchemy.sql.expression.TableClause" title="sqlalchemy.sql.expression.TableClause"><tt class="xref py py-class docutils literal">TableClause</tt></a>.

2179

E.g.:

2180

<div class="highlight-python"><div class="highlight"><pre>table.update().where(table.c.id==7).values(name='foo')</pre></div>

2181

</div>

2182

See <a class="reference internal" href="dml.html#sqlalchemy.sql.expression.update" title="sqlalchemy.sql.expression.update"><tt class="xref py py-func docutils literal">update()</tt></a> for argument and usage information.

2183

</dd></dl>

2184

2185

</dd></dl>

2186

2187

2188

2189

class <tt class="descclassname">sqlalchemy.schema.</tt><tt class="descname">ThreadLocalMetaData</tt><a class="headerlink" href="#sqlalchemy.schema.ThreadLocalMetaData" title="Permalink to this definition">¶</a></dt>

2190

<dd>Bases: <a class="reference internal" href="#sqlalchemy.schema.MetaData" title="sqlalchemy.schema.MetaData"><tt class="xref py py-class docutils literal">sqlalchemy.schema.MetaData</tt></a>

2191

A MetaData variant that presents a different <tt class="docutils literal">bind</tt> in every thread.

2192

Makes the <tt class="docutils literal">bind</tt> property of the MetaData a thread-local value, allowing

2193

this collection of tables to be bound to different <tt class="docutils literal">Engine</tt>

2194

implementations or connections in each thread.

2195

The ThreadLocalMetaData starts off bound to None in each thread. Binds

2196

must be made explicitly by assigning to the <tt class="docutils literal">bind</tt> property or using

2197

<tt class="docutils literal">connect()</tt>. You can also re-bind dynamically multiple times per

2198

thread, just like a regular <tt class="docutils literal">MetaData</tt>.

2199

2200

2201

2202

<dd>Construct a ThreadLocalMetaData.

2203

</dd></dl>

2204

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2208

<dd>The bound Engine or Connection for this thread.

2209

This property may be assigned an Engine or Connection, or assigned a

2210

string or URL to automatically create a basic Engine for this bind

2211

with <tt class="docutils literal">create_engine()</tt>.

2212

</dd></dl>

2213

2214

2215

2216

<tt class="descname">dispose</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.schema.ThreadLocalMetaData.dispose" title="Permalink to this definition">¶</a></dt>

2217

<dd>Dispose all bound engines, in all thread contexts.

2218

</dd></dl>

2219

2220

2221

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<tt class="descname">is_bound</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.schema.ThreadLocalMetaData.is_bound" title="Permalink to this definition">¶</a></dt>

2223

<dd>True if there is a bind for this thread.

2224

</dd></dl>

2225

2226

</dd></dl>

2227

2228

</div>

2229

</div>

2230

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</div>

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</div>

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<a href="schema.html" title="previous chapter">Schema Definition Language</a>

2238

<a href="reflection.html" title="next chapter">Reflecting Database Objects</a>

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</body>

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