~ubuntu-branches/ubuntu/trusty/postgresql-9.3/trusty-updates : contents of doc/src/sgml/html/sql-createeventtrigger.html at revision 27

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><H1
><A
NAME="SQL-CREATEEVENTTRIGGER"
></A
>CREATE EVENT TRIGGER</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN70286"
></A
><H2
>Name</H2
>CREATE EVENT TRIGGER&nbsp;--&nbsp;define a new event trigger</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN70291"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>CREATE EVENT TRIGGER <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>
  ON <TT
CLASS="REPLACEABLE"
><I
>event</I
></TT
>
  [ WHEN <TT
CLASS="REPLACEABLE"
><I
>filter_variable</I
></TT
> IN (filter_value [, ... ]) [ AND ... ] ]
  EXECUTE PROCEDURE <TT
CLASS="REPLACEABLE"
><I
>function_name</I
></TT
>()</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN70297"
></A
><H2
>Description</H2
><P
>   <TT
CLASS="COMMAND"
>CREATE EVENT TRIGGER</TT
> creates a new event trigger.
   Whenever the designated event occurs and the <TT
CLASS="LITERAL"
>WHEN</TT
> condition
   associated with the trigger, if any, is satisfied, the trigger function
   will be executed.  For a general introduction to event triggers, see
   <A
HREF="event-triggers.html"
>Chapter 37</A
>.  The user who creates an event trigger
   becomes its owner.
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN70303"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
></DT
><DD
><P
>      The name to give the new trigger.  This name must be unique within
      the database.
     </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>event</I
></TT
></DT
><DD
><P
>      The name of the event that triggers a call to the given function.
      See <A
HREF="event-trigger-definition.html"
>Section 37.1</A
> for more information
      on event names.
     </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>filter_variable</I
></TT
></DT
><DD
><P
>      The name of a variable used to filter events.  This makes it possible
      to restrict the firing of the trigger to a subset of the cases in which
      it is supported.  Currently the only supported
      <TT
CLASS="REPLACEABLE"
><I
>filter_variable</I
></TT
>
      is <TT
CLASS="LITERAL"
>TAG</TT
>.
     </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>filter_value</I
></TT
></DT
><DD
><P
>      A list of values for the
      associated <TT
CLASS="REPLACEABLE"
><I
>filter_variable</I
></TT
>
      for which the trigger should fire.  For <TT
CLASS="LITERAL"
>TAG</TT
>, this means a
      list of command tags (e.g. <TT
CLASS="LITERAL"
>'DROP FUNCTION'</TT
>).
     </P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>function_name</I
></TT
></DT
><DD
><P
>      A user-supplied function that is declared as taking no argument and
      returning type <TT
CLASS="LITERAL"
>event_trigger</TT
>.
     </P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="SQL-CREATEEVENTTRIGGER-NOTES"
></A
><H2
>Notes</H2
><P
>   Only superusers can create event triggers.
  </P
><P
>   Event triggers are disabled in single-user mode (see <A
HREF="app-postgres.html"
><SPAN
CLASS="APPLICATION"
>postgres</SPAN
></A
>).  If an erroneous event trigger disables the
   database so much that you can't even drop the trigger, restart in
   single-user mode and you'll be able to do that.
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="SQL-CREATEEVENTTRIGGER-EXAMPLES"
></A
><H2
>Examples</H2
><P
>   Forbid the execution of any <A
HREF="ddl.html"
>DDL</A
> command:

</P><PRE
CLASS="PROGRAMLISTING"
>CREATE OR REPLACE FUNCTION abort_any_command()
  RETURNS event_trigger
 LANGUAGE plpgsql
  AS $$
BEGIN
  RAISE EXCEPTION 'command % is disabled', tg_tag;
END;
$$;

CREATE EVENT TRIGGER abort_ddl ON ddl_command_start
   EXECUTE PROCEDURE abort_any_command();</PRE
><P></P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="SQL-CREATEEVENTTRIGGER-COMPATIBILITY"
></A
><H2
>Compatibility</H2
><P
>   There is no <TT
CLASS="COMMAND"
>CREATE EVENT TRIGGER</TT
> statement in the
   SQL standard.
  </P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN70352"
></A
><H2
>See Also</H2
><A
HREF="sql-altereventtrigger.html"
>ALTER EVENT TRIGGER</A
>, <A
HREF="sql-dropeventtrigger.html"
>DROP EVENT TRIGGER</A
>, <A
HREF="sql-createfunction.html"
>CREATE FUNCTION</A
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