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First files for reference pages.
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Thomas G. Lockhart
267
doc/src/sgml/ref/create_function.sgml
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267
doc/src/sgml/ref/create_function.sgml
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<REFENTRY ID="SQL-CREATEFUNCTION-1">
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<REFMETA>
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<REFENTRYTITLE>
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CREATE FUNCTION
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</REFENTRYTITLE>
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<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
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</REFMETA>
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<REFNAMEDIV>
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<REFNAME>
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CREATE FUNCTION
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</REFNAME>
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<REFPURPOSE>
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Defines a new function
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</REFPURPOSE>
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<REFSYNOPSISDIV>
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<REFSYNOPSISDIVINFO>
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<DATE>1998-04-15</DATE>
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</REFSYNOPSISDIVINFO>
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<SYNOPSIS>
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CREATE FUNCTION <replaceable class="parameter">name</replaceable> ([<replaceable class="parameter">ftype</replaceable> [, ...]])
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RETURNS <replaceable class="parameter">rtype</replaceable>
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AS <replaceable class="parameter">path</replaceable>
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LANGUAGE '<replaceable class="parameter">langname</replaceable>'
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</SYNOPSIS>
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<REFSECT2 ID="R2-SQL-CREATEFUNCTION-1">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Inputs
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</TITLE>
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<PARA>
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</PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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</TERM>
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<LISTITEM>
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<PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<replaceable class="parameter">name</replaceable>
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</TERM>
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<LISTITEM>
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<PARA>
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The name of a function to create.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<replaceable class="parameter">ftype</replaceable>
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</TERM>
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<LISTITEM>
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<PARA>
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The data type of function arguments.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<replaceable class="parameter">rtype</replaceable>
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</TERM>
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<LISTITEM>
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<PARA>
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The return data type.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<replaceable class="parameter">path</replaceable>
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</TERM>
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<LISTITEM>
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<PARA>
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May be either an SQL-query or an absolute path to an
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object file.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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<VARLISTENTRY>
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<TERM>
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<replaceable class="parameter">langname</replaceable>
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</TERM>
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<LISTITEM>
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<PARA>
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may be '<literal>c</literal>', '<literal>sql</literal>', '<literal>internal</literal>' or '<replaceable class="parameter">plname</replaceable>'.
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(where '<replaceable class="parameter">plname</replaceable>' is the language name of a created procedural
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language. See <command>CREATE LANGUAGE</command> for details).
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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</variablelist>
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</LISTITEM>
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</VARLISTENTRY>
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</VARIABLELIST>
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</REFSECT2>
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<REFSECT2 ID="R2-SQL-CREATEFUNCTION-2">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Outputs
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</TITLE>
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<PARA>
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</PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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</TERM>
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<LISTITEM>
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<PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue>CREATE</ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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This is returned if the command completes successfully.
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</PARA>
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</LISTITEM>
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</VARLISTENTRY>
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</variablelist>
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</LISTITEM>
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</VARLISTENTRY>
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</VARIABLELIST>
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</REFSECT2>
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</REFSYNOPSISDIV>
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<REFSECT1 ID="R1-SQL-CREATEFUNCTION-1">
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<REFSECT1INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT1INFO>
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<TITLE>
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Description
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</TITLE>
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<PARA>
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With this command, a PostgreSQL user can register a function
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with PostgreSQL. Subsequently, this user is treated as the
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owner of the function.
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</PARA>
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<REFSECT2 ID="R2-SQL-CREATEFUNCTION-3">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Notes
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</TITLE>
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<PARA>
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Refer to <citetitle>PostgreSQL User's Guide</citetitle> chapter 6 for further information.
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<comment>This reference needs to be corrected.</comment>
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</PARA>
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<PARA>
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Refer to the <citerefentry>
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<refentrytitle>DROP FUNCTION</refentrytitle>
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</citerefentry> statement to drop functions.
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</PARA>
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</REFSECT2>
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<REFSECT1 ID="R1-SQL-CREATEFUNCTION-2">
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<TITLE>
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Usage
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</TITLE>
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<PARA>
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To create a simple SQL function:
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</PARA>
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<ProgramListing>
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CREATE FUNCTION one() RETURNS int4
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AS 'SELECT 1 AS RESULT'
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LANGUAGE 'sql';
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SELECT one() AS answer;
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<computeroutput>answer
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------
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1 </computeroutput>
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</ProgramListing>
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<para>
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To create a C function, calling a routine from a user-created
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shared library. This particular routine calculates a check
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digit and returns TRUE if the check digit in the function parameters
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is correct. It is intended for use in a CHECK contraint.
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</para>
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<programlisting>
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<userinput>CREATE FUNCTION ean_checkdigit(bpchar, bpchar) RETURNS bool
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AS '/usr1/proj/bray/sql/funcs.so' LANGUAGE 'c';
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CREATE TABLE product
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(
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id char(8) PRIMARY KEY,
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eanprefix char(8) CHECK (eanprefix ~ '[0-9]{2}-[0-9]{5}')
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REFERENCES brandname(ean_prefix),
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eancode char(6) CHECK (eancode ~ '[0-9]{6}'),
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CONSTRAINT ean CHECK (ean_checkdigit(eanprefix, eancode))
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);</userinput>
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</programlisting>
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</REFSECT1>
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<REFSECT1 ID="R1-SQL-CREATEFUNCTION-3">
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<TITLE>
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Bugs
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</TITLE>
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<PARA>
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A C function cannot return a set of values.
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</PARA>
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</REFSECT1>
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<REFSECT1 ID="R1-SQL-CREATEFUNCTION-4">
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<TITLE>
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Compatibility
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</TITLE>
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<PARA>
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The CREATE FUNCTION statement is a PostgreSQL language extension.
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</PARA>
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<REFSECT2 ID="R2-SQL-CREATEFUNCTION-4">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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SQL/PSM<footnote>
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<para>
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PSM stands for Persistent Stored Modules, it is a procedural
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language and it was originally hoped that PSM would be ratified
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as an official standard by late 1996. However PSM will
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eventually become a standard.
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</para>
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</footnote>
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</TITLE>
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<para>
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The SQL/PSM CREATE FUNCTION statement has the following syntax:
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<programlisting>
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CREATE FUNCTION <replaceable class="parameter">name</replaceable>
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( [ [IN|OUT|INOUT] <replaceable class="parameter">parm</replaceable> <replaceable class="parameter">type</replaceable> [, ...] ])
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RETURNS <replaceable class="parameter">rtype</replaceable>
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LANGUAGE '<replaceable class="parameter">langname</replaceable>'
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ESPECIFIC <replaceable class="parameter">routine</replaceable>
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<replaceable class="parameter">SQL-statement</replaceable>
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</programlisting>
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</para>
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</refsect2>
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</refsect1>
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</REFENTRY>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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sgml-parent-document:nil
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sgml-default-dtd-file:"../reference.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:"/usr/lib/sgml/catalog"
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sgml-local-ecat-files:nil
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End:
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-->
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