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$PostgreSQL: pgsql/doc/src/sgml/ref/create_constraint.sgml,v 1.17 2006/10/17 12:53:03 momjian Exp $
PostgreSQL documentation
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<refentry id="SQL-CREATECONSTRAINT">
 <refmeta>
  <refentrytitle id="sql-createconstraint-title">CREATE CONSTRAINT TRIGGER</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>CREATE CONSTRAINT TRIGGER</refname>
  <refpurpose>define a new constraint trigger</refpurpose>
 </refnamediv>

 <indexterm zone="sql-createconstraint">
  <primary>CREATE CONSTRAINT</primary>
 </indexterm>

 <refsynopsisdiv>
<synopsis>
CREATE CONSTRAINT TRIGGER <replaceable class="parameter">name</replaceable>
    AFTER <replaceable class="parameter">event [ OR ... ]</replaceable>
    ON <replaceable class="parameter">table_name</replaceable>
    [ FROM <replaceable class="parameter">referenced_table_name</replaceable> ]
    { NOT DEFERRABLE | [ DEFERRABLE ] { INITIALLY IMMEDIATE | INITIALLY DEFERRED } }
    FOR EACH ROW
    EXECUTE PROCEDURE <replaceable class="parameter">funcname</replaceable> ( <replaceable class="parameter">arguments</replaceable> )
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE CONSTRAINT TRIGGER</command> is used within
   <command>CREATE TABLE</command>/<command>ALTER TABLE</command> and by
   <application>pg_dump</application> to create the special triggers for
   referential integrity.
    It is not intended for general use.
   </para>
  </refsect1>

  <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="PARAMETER">name</replaceable></term>
    <listitem>
     <para>
      The name of the constraint trigger. The actual name of the
      created trigger will be of the form
      <literal>RI_ConstraintTrigger_0000</literal> (where 0000 is some number
      assigned by the server).
      Use this assigned name when dropping the trigger.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="PARAMETER">event</replaceable></term>
    <listitem>
     <para>
      One of <literal>INSERT</literal>, <literal>UPDATE</literal>, or
      <literal>DELETE</literal>; this specifies the event that will fire the
      trigger. Multiple events can be specified using <literal>OR</literal>.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="PARAMETER">table_name</replaceable></term>
    <listitem>
     <para>
      The (possibly schema-qualified) name of the table in which
      the triggering events occur.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="PARAMETER">referenced_table_name</replaceable></term>
    <listitem>
     <para>
      The (possibly schema-qualified) name of the table referenced by the
      constraint. Used by foreign key constraints triggers.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>DEFERRABLE</literal></term>
    <term><literal>NOT DEFERRABLE</literal></term>
    <term><literal>INITIALLY IMMEDIATE</literal></term>
    <term><literal>INITIALLY DEFERRED</literal></term>
    <listitem>
     <para>
      See the <xref linkend="SQL-CREATETABLE" endterm="SQL-CREATETABLE-TITLE">
      documentation for details of these constraint options.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="PARAMETER">funcname</replaceable>(<replaceable class="PARAMETER">args</replaceable>)</term>
    <listitem>
     <para>
      The function to call as part of the trigger processing. See <xref
      linkend="SQL-CREATETRIGGER" endterm="SQL-CREATETRIGGER-TITLE"> for
      details.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
  </refsect1>

 <refsect1>
  <title>Compatibility</title>
  <para>
   <command>CREATE CONTRAINT TRIGGER</command> is a
   <productname>PostgreSQL</productname> extension of the <acronym>SQL</>
   standard.
  </para>
 </refsect1>

 </refentry>