Home • Explore • Blog • CI
☰



postgresql
3rd chunk of `doc/src/sgml/ref/create_rule.sgml`
1ea171b4e14d86c48d2775425b40edcdb84286ce9b54482c0000000100000ac6
 updatable view instead.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">table_name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of the table or view the
      rule applies to.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">condition</replaceable></term>
    <listitem>
     <para>
      Any <acronym>SQL</acronym> conditional expression (returning
      <type>boolean</type>).  The condition expression cannot refer
      to any tables except <literal>NEW</literal> and <literal>OLD</literal>, and
      cannot contain aggregate functions.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><option>INSTEAD</option></term>
    <listitem>
     <para><literal>INSTEAD</literal> indicates that the commands should be
      executed <emphasis>instead of</emphasis> the original command.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><option>ALSO</option></term>
    <listitem>
     <para><literal>ALSO</literal> indicates that the commands should be
      executed <emphasis>in addition to</emphasis> the original
      command.
     </para>

     <para>
      If neither <literal>ALSO</literal> nor
      <literal>INSTEAD</literal> is specified, <literal>ALSO</literal>
      is the default.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">command</replaceable></term>
    <listitem>
     <para>
      The command or commands that make up the rule action.  Valid
      commands are <command>SELECT</command>,
      <command>INSERT</command>, <command>UPDATE</command>,
      <command>DELETE</command>, or <command>NOTIFY</command>.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>

  <para>
   Within <replaceable class="parameter">condition</replaceable> and
   <replaceable class="parameter">command</replaceable>, the special
   table names <literal>NEW</literal> and <literal>OLD</literal> can
   be used to refer to values in the referenced table.
   <literal>NEW</literal> is valid in <literal>ON INSERT</literal> and
   <literal>ON UPDATE</literal> rules to refer to the new row being
   inserted or updated.  <literal>OLD</literal> is valid in
   <literal>ON UPDATE</literal> and <literal>ON DELETE</literal> rules
   to refer to the existing row being updated or deleted.
  </para>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   You must be the owner of a table to create or change rules for it.
  </para>

  <para>
   In a rule for <literal>INSERT</literal>, <literal>UPDATE</literal>, or
   <literal>DELETE</literal> on a view, you
Title: Parameters and Notes on Using CREATE RULE
Summary
The parameters for CREATE RULE include the event, table name, condition, INSTEAD/ALSO options, and command. INSTEAD means the command replaces the original, while ALSO means it's executed in addition. The default is ALSO if neither is specified. The command can be SELECT, INSERT, UPDATE, DELETE, or NOTIFY. In conditions and commands, NEW and OLD refer to values in the table. NEW is valid for INSERT and UPDATE rules, while OLD is valid for UPDATE and DELETE rules. Users must own a table to create or change its rules.