From 455dffbb73f9875c39f2ab544420454168a8c68c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Thu, 4 Dec 2008 17:51:28 +0000
Subject: Default values for function arguments

Pavel Stehule, with some tweaks by Peter Eisentraut
---
 doc/src/sgml/ref/create_function.sgml | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

(limited to 'doc/src/sgml/ref/create_function.sgml')

diff --git a/doc/src/sgml/ref/create_function.sgml b/doc/src/sgml/ref/create_function.sgml
index a6af57a22bf..5de4967789d 100644
--- a/doc/src/sgml/ref/create_function.sgml
+++ b/doc/src/sgml/ref/create_function.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.81 2008/11/14 10:22:46 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.82 2008/12/04 17:51:26 petere Exp $
 -->
 
 <refentry id="SQL-CREATEFUNCTION">
@@ -21,7 +21,7 @@ $PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.81 2008/11/14 10:22
  <refsynopsisdiv>
 <synopsis>
 CREATE [ OR REPLACE ] FUNCTION
-    <replaceable class="parameter">name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
+    <replaceable class="parameter">name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [ { DEFAULT | = } <replaceable class="parameter">defexpr</replaceable>] [, ...] ] )
     [ RETURNS <replaceable class="parameter">rettype</replaceable>
       | RETURNS TABLE ( <replaceable class="parameter">colname</replaceable> <replaceable class="parameter">coltype</replaceable> [, ...] ) ]
   { LANGUAGE <replaceable class="parameter">langname</replaceable>
@@ -154,6 +154,20 @@ CREATE [ OR REPLACE ] FUNCTION
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><replaceable class="parameter">defexpr</replaceable></term>
+
+     <listitem>
+      <para>
+       An expression to be used as default value if the parameter is
+       not specified.  The expression has to be convertable to the
+       argument type of the parameter.  All parameters after a
+       parameter with default value have to be parameters with default
+       values as well.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable class="parameter">rettype</replaceable></term>
 
@@ -667,6 +681,14 @@ COMMIT;
    either before or after <replaceable class="parameter">argname</replaceable>.
    But only the first way is standard-compliant.
   </para>
+
+  <para>
+   The SQL standard does not specify parameter defaults.  The syntax
+   with the <literal>DEFAULT</literal> key word is from Oracle, and it
+   is somewhat in the spirit of the standard: SQL/PSM uses it for
+   variable default values.  The syntax with <literal>=</literal> is
+   used in T-SQL and Firebird.
+  </para>
  </refsect1>
 
 
-- 
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