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>34.2. Data Types</A
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><P
> The columns of the information schema views use special data types
that are defined in the information schema. These are defined as
simple domains over ordinary built-in types. You should not use
these types for work outside the information schema, but your
applications must be prepared for them if they select from the
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> These types are:
<P
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><DT
><TT
CLASS="TYPE"
>cardinal_number</TT
></DT
><DD
><P
> A nonnegative integer.
</P
></DD
><DT
><TT
CLASS="TYPE"
>character_data</TT
></DT
><DD
><P
> A character string (without specific maximum length).
</P
></DD
><DT
><TT
CLASS="TYPE"
>sql_identifier</TT
></DT
><DD
><P
> A character string. This type is used for SQL identifiers, the
type <TT
CLASS="TYPE"
>character_data</TT
> is used for any other kind of
text data.
</P
></DD
><DT
><TT
CLASS="TYPE"
>time_stamp</TT
></DT
><DD
><P
> A domain over the type <TT
CLASS="TYPE"
>timestamp with time zone</TT
>
</P
></DD
><DT
><TT
CLASS="TYPE"
>yes_or_no</TT
></DT
><DD
><P
> A character string domain that contains
either <TT
CLASS="LITERAL"
>YES</TT
> or <TT
CLASS="LITERAL"
>NO</TT
>. This
is used to represent Boolean (true/false) data in the
information schema. (The information schema was invented
before the type <TT
CLASS="TYPE"
>boolean</TT
> was added to the SQL
standard, so this convention is necessary to keep the
information schema backward compatible.)
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Every column in the information schema has one of these five types.
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