1999-06-14 09:37:05 +02:00
|
|
|
<refentry id="SQL-CREATEFUNCTION">
|
|
|
|
<refmeta>
|
|
|
|
<refentrytitle>
|
1998-05-13 07:34:00 +02:00
|
|
|
CREATE FUNCTION
|
1999-06-14 09:37:05 +02:00
|
|
|
</refentrytitle>
|
|
|
|
<refmiscinfo>SQL - Language Statements</refmiscinfo>
|
|
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
|
|
<refname>
|
1998-05-13 07:34:00 +02:00
|
|
|
CREATE FUNCTION
|
1999-06-14 09:37:05 +02:00
|
|
|
</refname>
|
|
|
|
<refpurpose>
|
1998-05-13 07:34:00 +02:00
|
|
|
Defines a new function
|
1999-06-14 09:37:05 +02:00
|
|
|
</refpurpose>
|
1998-12-29 03:24:47 +01:00
|
|
|
</refnamediv>
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsynopsisdiv>
|
|
|
|
<refsynopsisdivinfo>
|
|
|
|
<date>1998-09-09</date>
|
|
|
|
</refsynopsisdivinfo>
|
|
|
|
<synopsis>
|
1998-09-16 16:43:12 +02:00
|
|
|
CREATE FUNCTION <replaceable class="parameter">name</replaceable> ( [ <replaceable class="parameter">ftype</replaceable> [, ...] ] )
|
|
|
|
RETURNS <replaceable class="parameter">rtype</replaceable>
|
1999-05-20 04:57:15 +02:00
|
|
|
AS <replaceable class="parameter">definition</replaceable>
|
1998-09-16 16:43:12 +02:00
|
|
|
LANGUAGE '<replaceable class="parameter">langname</replaceable>'
|
1999-06-14 09:37:05 +02:00
|
|
|
</synopsis>
|
1998-05-13 07:34:00 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect2 id="R2-SQL-CREATEFUNCTION-1">
|
|
|
|
<refsect2info>
|
|
|
|
<date>1998-09-09</date>
|
|
|
|
</refsect2info>
|
|
|
|
<title>
|
1998-05-13 07:34:00 +02:00
|
|
|
Inputs
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
|
|
|
<para>
|
1999-07-06 19:16:42 +02:00
|
|
|
|
|
|
|
<variablelist>
|
|
|
|
<varlistentry>
|
|
|
|
<term><replaceable class="parameter">name</replaceable></term>
|
|
|
|
<listitem>
|
|
|
|
<para>
|
|
|
|
The name of a function to create.
|
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
|
|
<term><replaceable class="parameter">ftype</replaceable></term>
|
|
|
|
<listitem>
|
|
|
|
<para>
|
|
|
|
The data type of function arguments.
|
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
|
|
<term><replaceable class="parameter">rtype</replaceable></term>
|
|
|
|
<listitem>
|
|
|
|
<para>
|
|
|
|
The return data type.
|
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
|
|
<term><replaceable class="parameter">definition</replaceable></term>
|
1999-06-14 09:37:05 +02:00
|
|
|
<listitem>
|
|
|
|
<para>
|
1999-05-20 04:57:15 +02:00
|
|
|
A string defining the function; the meaning depends on the language.
|
|
|
|
It may be an internal function name, the path to an object file,
|
|
|
|
an SQL query, or text in a procedural language.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
1999-07-06 19:16:42 +02:00
|
|
|
<term><replaceable class="parameter">langname</replaceable></term>
|
1999-06-14 09:37:05 +02:00
|
|
|
<listitem>
|
|
|
|
<para>
|
1998-12-29 03:24:47 +01:00
|
|
|
may be '<literal>C</literal>', '<literal>sql</literal>',
|
|
|
|
'<literal>internal</literal>'
|
|
|
|
or '<replaceable class="parameter">plname</replaceable>',
|
|
|
|
where '<replaceable class="parameter">plname</replaceable>'
|
|
|
|
is the name of a created procedural
|
|
|
|
language. See <command>CREATE LANGUAGE</command> for details.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
1998-12-29 03:24:47 +01:00
|
|
|
</variablelist>
|
|
|
|
</para>
|
1999-06-14 09:37:05 +02:00
|
|
|
</refsect2>
|
1999-07-06 19:16:42 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect2 id="R2-SQL-CREATEFUNCTION-2">
|
|
|
|
<refsect2info>
|
|
|
|
<date>1998-09-09</date>
|
|
|
|
</refsect2info>
|
|
|
|
<title>
|
1998-05-13 07:34:00 +02:00
|
|
|
Outputs
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
|
|
|
<para>
|
1999-07-06 19:16:42 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<variablelist>
|
|
|
|
<varlistentry>
|
1999-07-06 19:16:42 +02:00
|
|
|
<term><computeroutput>
|
|
|
|
CREATE
|
|
|
|
</computeroutput></term>
|
1999-06-14 09:37:05 +02:00
|
|
|
<listitem>
|
|
|
|
<para>
|
1998-12-29 03:24:47 +01:00
|
|
|
This is returned if the command completes successfully.
|
|
|
|
</para>
|
|
|
|
</listitem>
|
|
|
|
</varlistentry>
|
1999-06-14 09:37:05 +02:00
|
|
|
</variablelist>
|
1998-12-29 03:24:47 +01:00
|
|
|
</para>
|
1999-06-14 09:37:05 +02:00
|
|
|
</refsect2>
|
|
|
|
</refsynopsisdiv>
|
1999-07-06 19:16:42 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect1 id="R1-SQL-CREATEFUNCTION-1">
|
|
|
|
<refsect1info>
|
|
|
|
<date>1998-09-09</date>
|
|
|
|
</refsect1info>
|
|
|
|
<title>
|
1998-05-13 07:34:00 +02:00
|
|
|
Description
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
|
|
|
<para>
|
1998-09-16 16:43:12 +02:00
|
|
|
<command>CREATE FUNCTION</command> allows a
|
1998-12-29 03:24:47 +01:00
|
|
|
<productname>Postgres</productname> user
|
|
|
|
to register a function
|
1998-09-16 16:43:12 +02:00
|
|
|
with a database. Subsequently, this user is treated as the
|
1998-05-13 07:34:00 +02:00
|
|
|
owner of the function.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
1998-05-13 07:34:00 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect2 id="R2-SQL-CREATEFUNCTION-3">
|
|
|
|
<refsect2info>
|
|
|
|
<date>1998-09-09</date>
|
|
|
|
</refsect2info>
|
|
|
|
<title>
|
1998-05-13 07:34:00 +02:00
|
|
|
Notes
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
|
|
|
<para>
|
1998-09-16 16:43:12 +02:00
|
|
|
Refer to the chapter on functions
|
|
|
|
in the <citetitle>PostgreSQL Programmer's Guide</citetitle>
|
1998-12-29 03:24:47 +01:00
|
|
|
for further information.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
|
|
|
<para>
|
1998-09-16 16:43:12 +02:00
|
|
|
Use <command>DROP FUNCTION</command>
|
|
|
|
to drop user-defined functions.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
1999-05-20 04:57:15 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<para>
|
1999-05-20 04:57:15 +02:00
|
|
|
<productname>Postgres</productname> allows function "overloading";
|
|
|
|
that is, the same name can be used for several different functions
|
|
|
|
so long as they have distinct argument types. This facility must be
|
|
|
|
used with caution for INTERNAL and C-language functions, however.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
1999-05-20 04:57:15 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<para>
|
1999-05-20 04:57:15 +02:00
|
|
|
Two INTERNAL functions cannot have the same C name without causing
|
|
|
|
errors at link time. To get around that, give them different C names
|
|
|
|
(for example, use the argument types as part of the C names), then
|
|
|
|
specify those names in the AS clause of <command>CREATE FUNCTION</command>.
|
|
|
|
If the AS clause is left empty then <command>CREATE FUNCTION</command>
|
|
|
|
assumes the C name of the function is the same as the SQL name.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
1999-05-20 04:57:15 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<para>
|
1999-05-20 04:57:15 +02:00
|
|
|
For dynamically-loaded C functions, the SQL name of the function must
|
|
|
|
be the same as the C function name, because the AS clause is used to
|
|
|
|
give the path name of the object file containing the C code. In this
|
|
|
|
situation it is best not to try to overload SQL function names. It
|
|
|
|
might work to load a C function that has the same C name as an internal
|
|
|
|
function or another dynamically-loaded function --- or it might not.
|
|
|
|
On some platforms the dynamic loader may botch the load in interesting
|
|
|
|
ways if there is a conflict of C function names. So, even if it works
|
|
|
|
for you today, you might regret overloading names later when you try
|
|
|
|
to run the code somewhere else.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
|
|
|
</refsect2>
|
1998-12-29 03:24:47 +01:00
|
|
|
</refsect1>
|
1998-05-13 07:34:00 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect1 id="R1-SQL-CREATEFUNCTION-2">
|
|
|
|
<title>
|
1998-05-13 07:34:00 +02:00
|
|
|
Usage
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
|
|
|
<para>
|
1998-05-13 07:34:00 +02:00
|
|
|
To create a simple SQL function:
|
1999-07-06 19:16:42 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<programlisting>
|
1999-07-06 19:16:42 +02:00
|
|
|
CREATE FUNCTION one() RETURNS int4
|
|
|
|
AS 'SELECT 1 AS RESULT'
|
|
|
|
LANGUAGE 'sql';
|
|
|
|
SELECT one() AS answer;
|
|
|
|
|
1998-12-29 03:24:47 +01:00
|
|
|
<computeroutput>
|
|
|
|
answer
|
|
|
|
------
|
|
|
|
1
|
|
|
|
</computeroutput>
|
1999-06-14 09:37:05 +02:00
|
|
|
</programlisting>
|
1999-07-06 19:16:42 +02:00
|
|
|
</para>
|
|
|
|
|
1998-05-13 07:34:00 +02:00
|
|
|
<para>
|
|
|
|
To create a C function, calling a routine from a user-created
|
|
|
|
shared library. This particular routine calculates a check
|
|
|
|
digit and returns TRUE if the check digit in the function parameters
|
|
|
|
is correct. It is intended for use in a CHECK contraint.
|
|
|
|
</para>
|
|
|
|
<programlisting>
|
1998-12-29 03:24:47 +01:00
|
|
|
<userinput>
|
1999-07-06 19:16:42 +02:00
|
|
|
CREATE FUNCTION ean_checkdigit(bpchar, bpchar) RETURNS bool
|
|
|
|
AS '/usr1/proj/bray/sql/funcs.so' LANGUAGE 'c';
|
1998-12-29 03:24:47 +01:00
|
|
|
|
1999-07-06 19:16:42 +02:00
|
|
|
CREATE TABLE product (
|
1999-06-14 09:37:05 +02:00
|
|
|
id char(8) PRIMARY KEY,
|
|
|
|
eanprefix char(8) CHECK (eanprefix ~ '[0-9]{2}-[0-9]{5}')
|
|
|
|
REFERENCES brandname(ean_prefix),
|
|
|
|
eancode char(6) CHECK (eancode ~ '[0-9]{6}'),
|
|
|
|
CONSTRAINT ean CHECK (ean_checkdigit(eanprefix, eancode))
|
1999-07-06 19:16:42 +02:00
|
|
|
);
|
1999-06-14 09:37:05 +02:00
|
|
|
</userinput>
|
1998-05-13 07:34:00 +02:00
|
|
|
</programlisting>
|
1999-06-14 09:37:05 +02:00
|
|
|
</refsect1>
|
1998-05-13 07:34:00 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect1 id="R1-SQL-CREATEFUNCTION-3">
|
|
|
|
<title>
|
1998-05-13 07:34:00 +02:00
|
|
|
Bugs
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
|
|
|
<para>
|
1998-05-13 07:34:00 +02:00
|
|
|
A C function cannot return a set of values.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
|
|
|
</refsect1>
|
1999-07-06 19:16:42 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect1 id="R1-SQL-CREATEFUNCTION-4">
|
|
|
|
<title>
|
1998-05-13 07:34:00 +02:00
|
|
|
Compatibility
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
1999-07-06 19:16:42 +02:00
|
|
|
<para>
|
|
|
|
<command>CREATE FUNCTION</command> is
|
|
|
|
a <productname>Postgres</productname> language extension.
|
1999-06-14 09:37:05 +02:00
|
|
|
</para>
|
1999-07-06 19:16:42 +02:00
|
|
|
|
1999-06-14 09:37:05 +02:00
|
|
|
<refsect2 id="R2-SQL-CREATEFUNCTION-4">
|
|
|
|
<refsect2info>
|
|
|
|
<date>1998-09-09</date>
|
|
|
|
</refsect2info>
|
|
|
|
<title>
|
1998-09-16 16:43:12 +02:00
|
|
|
SQL/PSM
|
1999-06-14 09:37:05 +02:00
|
|
|
</title>
|
1998-09-16 16:43:12 +02:00
|
|
|
<para>
|
|
|
|
|
1999-07-06 19:16:42 +02:00
|
|
|
<note>
|
1998-05-13 07:34:00 +02:00
|
|
|
<para>
|
1998-09-16 16:43:12 +02:00
|
|
|
PSM stands for Persistent Stored Modules. It is a procedural
|
1998-05-13 07:34:00 +02:00
|
|
|
language and it was originally hoped that PSM would be ratified
|
1998-09-16 16:43:12 +02:00
|
|
|
as an official standard by late 1996. As of mid-1998, this
|
1999-07-06 19:16:42 +02:00
|
|
|
has not yet happened, but it is hoped that PSM will
|
1998-05-13 07:34:00 +02:00
|
|
|
eventually become a standard.
|
|
|
|
</para>
|
1999-07-06 19:16:42 +02:00
|
|
|
</note>
|
1998-09-16 16:43:12 +02:00
|
|
|
|
1999-07-06 19:16:42 +02:00
|
|
|
SQL/PSM <command>CREATE FUNCTION</command> has the following syntax:
|
|
|
|
<synopsis>
|
1998-09-16 16:43:12 +02:00
|
|
|
CREATE FUNCTION <replaceable class="parameter">name</replaceable>
|
1999-07-06 19:16:42 +02:00
|
|
|
( [ [ IN | OUT | INOUT ] <replaceable class="parameter">eter</replaceable>eable>eable> <replaceable
|
1999-06-14 09:37:05 +02:00
|
|
|
class="parameter">type</replaceable> [, ...] ] )
|
1998-09-16 16:43:12 +02:00
|
|
|
RETURNS <replaceable class="parameter">rtype</replaceable>
|
|
|
|
LANGUAGE '<replaceable class="parameter">langname</replaceable>'
|
|
|
|
ESPECIFIC <replaceable class="parameter">routine</replaceable>
|
|
|
|
<replaceable class="parameter">SQL-statement</replaceable>
|
1999-07-06 19:16:42 +02:00
|
|
|
</synopsis>
|
1998-05-13 07:34:00 +02:00
|
|
|
</para>
|
|
|
|
</refsect2>
|
|
|
|
</refsect1>
|
1999-06-14 09:37:05 +02:00
|
|
|
</refentry>
|
1998-05-13 07:34:00 +02:00
|
|
|
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
|
|
Local variables:
|
|
|
|
mode: sgml
|
1999-06-14 09:37:05 +02:00
|
|
|
sgml-omittag:nil
|
1998-05-13 07:34:00 +02:00
|
|
|
sgml-shorttag:t
|
|
|
|
sgml-minimize-attributes:nil
|
|
|
|
sgml-always-quote-attributes:t
|
|
|
|
sgml-indent-step:1
|
|
|
|
sgml-indent-data:t
|
|
|
|
sgml-parent-document:nil
|
|
|
|
sgml-default-dtd-file:"../reference.ced"
|
|
|
|
sgml-exposed-tags:nil
|
|
|
|
sgml-local-catalogs:"/usr/lib/sgml/catalog"
|
|
|
|
sgml-local-ecat-files:nil
|
|
|
|
End:
|
|
|
|
-->
|