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 <literal>CASE_NOT_FOUND</literal> exception is raised.
      </para>

      <para>
       Here is a simple example:

<programlisting>
CASE x
    WHEN 1, 2 THEN
        msg := 'one or two';
    ELSE
        msg := 'other value than one or two';
END CASE;
</programlisting>
      </para>
     </sect3>

     <sect3 id="plpgsql-conditionals-searched-case">
      <title>Searched <literal>CASE</literal></title>

<synopsis>
CASE
    WHEN <replaceable>boolean-expression</replaceable> THEN
      <replaceable>statements</replaceable>
  <optional> WHEN <replaceable>boolean-expression</replaceable> THEN
      <replaceable>statements</replaceable>
    ... </optional>
  <optional> ELSE
      <replaceable>statements</replaceable> </optional>
END CASE;
</synopsis>

      <para>
       The searched form of <command>CASE</command> provides conditional execution
       based on truth of Boolean expressions.  Each <literal>WHEN</literal> clause's
       <replaceable>boolean-expression</replaceable> is evaluated in turn,
       until one is found that yields <literal>true</literal>.  Then the
       corresponding <replaceable>statements</replaceable> are executed, and
       then control passes to the next statement after <literal>END CASE</literal>.
       (Subsequent <literal>WHEN</literal> expressions are not evaluated.)
       If no true result is found, the <literal>ELSE</literal>
       <replaceable>statements</replaceable> are executed;
       but if <literal>ELSE</literal> is not present, then a
       <literal>CASE_NOT_FOUND</literal> exception is raised.
      </para>

      <para>
       Here is an example:

<programlisting>
CASE
    WHEN x BETWEEN 0 AND 10 THEN
        msg := 'value is between zero and ten';
    WHEN x BETWEEN 11 AND 20 THEN
        msg := 'value is between eleven and twenty';
END CASE;
</programlisting>
      </para>

      <para>
       This form of <command>CASE</command> is entirely equivalent to
       <literal>IF-THEN-ELSIF</literal>, except for the rule that reaching
       an omitted <literal>ELSE</literal> clause results in an error rather
       than doing nothing.
      </para>

     </sect3>
   </sect2>

   <sect2 id="plpgsql-control-structures-loops">
    <title>Simple Loops</title>

    <indexterm zone="plpgsql-control-structures-loops">
     <primary>loop</primary>
     <secondary>in PL/pgSQL</secondary>
    </indexterm>

    <para>
     With the <literal>LOOP</literal>, <literal>EXIT</literal>,
     <literal>CONTINUE</literal>, <literal>WHILE</literal>, <literal>FOR</literal>,
     and <literal>FOREACH</literal> statements, you can arrange for your
     <application>PL/pgSQL</application> function to repeat a series of commands.
    </para>

    <sect3 id="plpgsql-control-structures-loops-loop">
     <title><literal>LOOP</literal></title>

<synopsis>
<optional> &lt;&lt;<replaceable>label</replaceable>&gt;&gt; </optional>
LOOP
    <replaceable>statements</replaceable>
END LOOP <optional> <replaceable>label</replaceable> </optional>;
</synopsis>

     <para>
      <literal>LOOP</literal> defines an unconditional loop that is repeated
      indefinitely until terminated by an <literal>EXIT</literal> or
      <command>RETURN</command> statement.  The optional
      <replaceable>label</replaceable> can be used by <literal>EXIT</literal>
      and <literal>CONTINUE</literal> statements within nested loops to
      specify which loop those statements refer to.
     </para>
    </sect3>

     <sect3 id="plpgsql-control-structures-loops-exit">
      <title><literal>EXIT</literal></title>

     <indexterm>
      <primary>EXIT</primary>
      <secondary>in PL/pgSQL</secondary>
     </indexterm>

<synopsis>
EXIT <optional> <replaceable>label</replaceable> </optional> <optional> WHEN <replaceable>boolean-expression</replaceable> </optional>;
</synopsis>

       <para>
        If no <replaceable>label</replaceable> is given, the innermost
        loop is terminated and the statement following <literal>END
        LOOP</literal>
Title: Searched CASE Statement and Simple Loops in PL/pgSQL
Summary
This section discusses the searched CASE statement, where conditional execution is based on the truth of boolean expressions. It evaluates each WHEN clause's boolean expression until one is true, executing the corresponding statements. If no expression is true, the ELSE statements are executed, or a CASE_NOT_FOUND exception is raised if ELSE is absent. Finally, the section introduces the LOOP statement, which creates an unconditional loop that repeats indefinitely until terminated by EXIT or RETURN. It mentions related statements like EXIT, CONTINUE, WHILE, FOR, and FOREACH. The section ends with the EXIT statement, which terminates the innermost loop if no label is given.