special variable named <literal>FOUND</literal>, which is of
     type <type>boolean</type>.  <literal>FOUND</literal> starts out
     false within each <application>PL/pgSQL</application> function call.
     It is set by each of the following types of statements:

         <itemizedlist>
          <listitem>
           <para>
            A <command>SELECT INTO</command> statement sets
            <literal>FOUND</literal> true if a row is assigned, false if no
            row is returned.
           </para>
          </listitem>
          <listitem>
           <para>
            A <command>PERFORM</command> statement sets <literal>FOUND</literal>
            true if it produces (and discards) one or more rows, false if
            no row is produced.
           </para>
          </listitem>
          <listitem>
           <para>
            <command>UPDATE</command>, <command>INSERT</command>, <command>DELETE</command>,
            and <command>MERGE</command>
            statements set <literal>FOUND</literal> true if at least one
            row is affected, false if no row is affected.
           </para>
          </listitem>
          <listitem>
           <para>
            A <command>FETCH</command> statement sets <literal>FOUND</literal>
            true if it returns a row, false if no row is returned.
           </para>
          </listitem>
          <listitem>
           <para>
            A <command>MOVE</command> statement sets <literal>FOUND</literal>
            true if it successfully repositions the cursor, false otherwise.
           </para>
          </listitem>
          <listitem>
           <para>
            A <command>FOR</command> or <command>FOREACH</command> statement sets
            <literal>FOUND</literal> true
            if it iterates one or more times, else false.
            <literal>FOUND</literal> is set this way when the
            loop exits; inside the execution of the loop,
            <literal>FOUND</literal> is not modified by the
            loop statement, although it might be changed by the
            execution of other statements within the loop body.
           </para>
          </listitem>
          <listitem>
           <para>
            <command>RETURN QUERY</command> and <command>RETURN QUERY
            EXECUTE</command> statements set <literal>FOUND</literal>
            true if the query returns at least one row, false if no row
            is returned.
           </para>
          </listitem>
         </itemizedlist>

     Other <application>PL/pgSQL</application> statements do not change
     the state of <literal>FOUND</literal>.
     Note in particular that <command>EXECUTE</command>
     changes the output of <command>GET DIAGNOSTICS</command>, but
     does not change <literal>FOUND</literal>.
    </para>

    <para>
     <literal>FOUND</literal> is a local variable within each
     <application>PL/pgSQL</application> function; any changes to it
     affect only the current function.
    </para>

   </sect2>

   <sect2 id="plpgsql-statements-null">
    <title>Doing Nothing At All</title>

    <para>
     Sometimes a placeholder statement that does nothing is useful.
     For example, it can indicate that one arm of an if/then/else
     chain is deliberately empty.  For this purpose, use the
     <command>NULL</command> statement:

<synopsis>
NULL;
</synopsis>
    </para>

    <para>
     For example, the following two fragments of code are equivalent:
<programlisting>
BEGIN
    y := x / 0;
EXCEPTION
    WHEN division_by_zero THEN
        NULL;  -- ignore the error
END;
</programlisting>

<programlisting>
BEGIN
    y := x / 0;
EXCEPTION
    WHEN division_by_zero THEN  -- ignore the error
END;
</programlisting>
     Which is preferable is a matter of taste.
    </para>

    <note>
     <para>
      In Oracle's PL/SQL, empty statement lists are not allowed, and so
      <command>NULL</command> statements are <emphasis>required</emphasis> for situations
      such as