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<chapter id="plpgsql">

<title><application>PL/pgSQL</application> - <acronym>SQL</acronym> Procedural Language</title>

</para>

</sect3>

<sect3>

<sect3 id="plpgsql-integer-for">

<title><literal>FOR</> (integer variant)</title>

<synopsis>

the lower and upper bound of the range are evaluated once when entering

the loop. If the <literal>BY</> clause isn't specified the iteration

step is 1, otherwise it's the value specified in the <literal>BY</>

clause. If <literal>REVERSE</> is specified then the step value is

clause, which again is evaluated once on loop entry.

If <literal>REVERSE</> is specified then the step value is

subtracted, rather than added, after each iteration.

</para>

<para>

Some examples of integer <literal>FOR</> loops:

<programlisting>

FOR i IN 1..10 LOOP

-- some computations here

RAISE NOTICE 'i is %', i;

-- i will take on the values 1,2,3,4,5,6,7,8,9,10 within the loop

END LOOP;

FOR i IN REVERSE 10..1 LOOP

--some computations here

--i will take on the values 10,9,8,7,6,5,4,3,2,1 within the loop

END LOOP;

FOR i IN REVERSE 10..1 BY 2 LOOP

-- some computations here

RAISE NOTICE 'i is %', i;

-- i will take on the values 10,8,6,4,2 within the loop

END LOOP;

</programlisting>

</para>

in the <literal>REVERSE</> case), the loop body is not

executed at all. No error is raised.

</para>

<para>

If a <replaceable>label</replaceable> is attached to the

<literal>FOR</> loop then the integer loop variable can be

referenced with a qualified name, using that

<replaceable>label</replaceable>.

</para>

</sect3>

</sect2>

</para>

</listitem>

<listitem>

<para>

Integer <command>FOR</> loops with <literal>REVERSE</> work

differently: <application>PL/SQL</> counts down from the second

number to the first, while <application>PL/pgSQL</> counts down

from the first number to the second, requiring the loop bounds

to be swapped when porting. This incompatibility is unfortunate

but is unlikely to be changed. (See <xref

linkend="plpgsql-integer-for">.)

</para>

</listitem>

</itemizedlist>

</para>