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<?xml version='1.0' encoding='iso-8859-1'?>
<!-- $Revision: 1.4 $ -->
<refentry id="function.PDO-sqliteCreateFunction">
<refnamediv>
<refname>PDO::sqliteCreateFunction</refname>
<refpurpose>
Registers a User Defined Function for use in SQL statements
</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>bool</type><methodname>PDO::sqliteCreateFunction</methodname>
<methodparam><type>string</type><parameter>function_name</parameter></methodparam>
<methodparam><type>callback</type><parameter>callback</parameter></methodparam>
<methodparam choice="opt"><type>int</type><parameter>num_args</parameter></methodparam>
</methodsynopsis>
&warn.experimental.func;
<para>
<function>PDO::sqliteCreateFunction</function> allows you to register a PHP
function with SQLite as an <acronym>UDF</acronym> (User Defined
Function), so that it can be called from within your SQL statements.
</para>
<para>
The UDF can be used in any SQL statement that can call functions, such as
SELECT and UPDATE statements and also in triggers.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>function_name</parameter></term>
<listitem>
<para>
The name of the function used in SQL statements.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>callback</parameter></term>
<listitem>
<para>
Callback function to handle the defined SQL function.
</para>
<note>
<simpara>
Callback functions should return a type understood by SQLite (i.e.
<link linkend="language.types.intro">scalar type</link>).
</simpara>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>num_args</parameter></term>
<listitem>
<para>
Hint to the SQLite parser if the callback function accepts a
predetermined number of arguments.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
&sqlite.param-compat;
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>PDO::sqliteCreateFunction</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
function md5_and_reverse($string)
{
return strrev(md5($string));
}
$db = new PDO('sqlite:sqlitedb');
$db->sqliteCreateFunction('md5rev', 'md5_and_reverse', 1);
$rows = $db->query('SELECT md5rev(filename) FROM files')->fetchAll();
?>
]]>
</programlisting>
</example>
</para>
<para>
In this example, we have a function that calculates the md5 sum of a
string, and then reverses it. When the SQL statement executes, it
returns the value of the filename transformed by our function. The data
returned in <parameter>$rows</parameter> contains the processed result.
</para>
<para>
The beauty of this technique is that you do not need to process the
result using a foreach() loop after you have queried for the data.
</para>
<!-- not for PDO it doesn't, at least not yet
<para>
PHP registers a special function named <literal>php</literal> when the
database is first opened. The php function can be used to call any PHP
function without having to register it first.
</para>
<para>
<example>
<title>Example of using the PHP function</title>
<programlisting role="php">
<![CDATA[
<?php
$rows = $db->query("SELECT php('md5', filename) from files")->fetchAll();
?>
]]>
</programlisting>
<para>
This example will call the <function>md5</function> on each
<literal>filename</literal> column in the database and return the result
into <parameter>$rows</parameter>
</para>
</example>
</para>
-->
<tip>
<para>
You can use <function>PDO::sqliteCreateFunction</function> and
<function>PDO::sqliteCreateAggregate</function> to override SQLite native
SQL functions.
</para>
</tip>
<note>
<para>
This method is not available with the SQLite2 driver.
Use the old style sqlite API for that instead.
</para>
</note>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>PDO::sqliteCreateAggregate</function></member>
<member><function>sqlite_create_function</function></member>
<member><function>sqlite_create_aggregate</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"../../../../manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->
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