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Add a CONTINUE statement to PL/PgSQL, which can be used to begin the

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next iteration of a loop. Update documentation and add regression tests.
Patch from Pavel Stehule, reviewed by Neil Conway.
This commit is contained in:
Neil Conway
2005-06-22 01:35:03 +00:00
parent 7a28de2052
commit ebcb4c931d
8 changed files with 501 additions and 80 deletions
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94
doc/src/sgml/plpgsql.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.73 2005/06/19 23:39:05 neilc Exp $
$PostgreSQL: pgsql/doc/src/sgml/plpgsql.sgml,v 1.74 2005/06/22 01:35:02 neilc Exp $
-->
<chapter id="plpgsql">
@ -1779,10 +1779,10 @@ END IF;
</indexterm>
<para>
With the <literal>LOOP</>, <literal>EXIT</>, <literal>WHILE</>,
and <literal>FOR</> statements, you can arrange for your
<application>PL/pgSQL</application> function to repeat a series
of commands.
With the <literal>LOOP</>, <literal>EXIT</>,
<literal>CONTINUE</>, <literal>WHILE</>, and <literal>FOR</>
statements, you can arrange for your <application>PL/pgSQL</>
function to repeat a series of commands.
</para>
<sect3>
@ -1807,30 +1807,36 @@ END LOOP;
<sect3>
<title><literal>EXIT</></title>
<indexterm>
<primary>EXIT</primary>
<secondary>in PL/pgSQL</secondary>
</indexterm>
<synopsis>
EXIT <optional> <replaceable>label</replaceable> </optional> <optional> WHEN <replaceable>expression</replaceable> </optional>;
</synopsis>
<para>
If no <replaceable>label</replaceable> is given,
the innermost loop is terminated and the
statement following <literal>END LOOP</> is executed next.
If <replaceable>label</replaceable> is given, it
must be the label of the current or some outer level of nested loop
or block. Then the named loop or block is terminated and control
continues with the statement after the loop's/block's corresponding
<literal>END</>.
If no <replaceable>label</replaceable> is given, the innermost
loop is terminated and the statement following <literal>END
LOOP</> is executed next. If <replaceable>label</replaceable>
is given, it must be the label of the current or some outer
level of nested loop or block. Then the named loop or block is
terminated and control continues with the statement after the
loop's/block's corresponding <literal>END</>.
</para>
<para>
If <literal>WHEN</> is present, loop exit occurs only if the specified
condition is true, otherwise control passes to the statement after
<literal>EXIT</>.
If <literal>WHEN</> is specified, the loop exit occurs only if
<replaceable>expression</> is true. Otherwise, control passes
to the statement after <literal>EXIT</>.
</para>
<para>
<literal>EXIT</> can be used to cause early exit from all types of
loops; it is not limited to use with unconditional loops.
<literal>EXIT</> can be used with all types of loops; it is
not limited to use with unconditional loops. When used with a
<literal>BEGIN</literal> block, <literal>EXIT</literal> passes
control to the next statement after the end of the block.
</para>
<para>
@ -1858,9 +1864,61 @@ END;
</para>
</sect3>
<sect3>
<title><literal>CONTINUE</></title>
<indexterm>
<primary>CONTINUE</primary>
<secondary>in PL/pgSQL</secondary>
</indexterm>
<synopsis>
CONTINUE <optional> <replaceable>label</replaceable> </optional> <optional> WHEN <replaceable>expression</replaceable> </optional>;
</synopsis>
<para>
If no <replaceable>label</> is given, the next iteration of
the innermost loop is begun. That is, control is passed back
to the loop control expression (if any), and the body of the
loop is re-evaluated. If <replaceable>label</> is present, it
specifies the label of the loop whose execution will be
continued.
</para>
<para>
If <literal>WHEN</> is specified, the next iteration of the
loop is begun only if <replaceable>expression</> is
true. Otherwise, control passes to the statement after
<literal>CONTINUE</>.
</para>
<para>
<literal>CONTINUE</> can be used with all types of loops; it
is not limited to use with unconditional loops.
</para>
<para>
Examples:
<programlisting>
LOOP
-- some computations
EXIT WHEN count &gt; 100;
CONTINUE WHEN count &lt; 50;
-- some computations for count IN [50 .. 100]
END LOOP;
</programlisting>
</para>
</sect3>
<sect3>
<title><literal>WHILE</></title>
<indexterm>
<primary>WHILE</primary>
<secondary>in PL/pgSQL</secondary>
</indexterm>
<synopsis>
<optional>&lt;&lt;<replaceable>label</replaceable>&gt;&gt;</optional>
WHILE <replaceable>expression</replaceable> LOOP