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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.4 $ -->
<!-- splitted from ./en/functions/dbx.xml, last change in rev 1.3 -->
<refentry id="function.dbx-compare">
<refnamediv>
<refname>dbx_compare</refname>
<refpurpose>Compare two rows for sorting purposes</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<methodsynopsis>
<type>int</type><methodname>dbx_compare</methodname>
<methodparam><type>array</type><parameter>row_a</parameter></methodparam>
<methodparam><type>array</type><parameter>row_b</parameter></methodparam>
<methodparam><type>string</type><parameter>column_key</parameter></methodparam>
<methodparam choice="opt"><type>int</type><parameter>flags</parameter></methodparam>
</methodsynopsis>
<para>
<function>dbx_compare</function> returns <literal>0</literal> if the
<literal>row_a[$column_key]</literal> is equal to
<literal>row_b[$column_key]</literal>, and <literal>1</literal> or
<literal>-1</literal> if the former is greater or is smaller than
the latter one, respectively, or vice versa if the
<parameter>flag</parameter> is set to <constant>DBX_CMP_DESC</constant>.
<function>dbx_compare</function> is a helper function for
<function>dbx_sort</function> to ease the make and use of the custom
sorting function.
</para>
<para>
The <parameter>flags</parameter> can be set to specify comparison
direction:
<itemizedlist>
<listitem>
<simpara>
<constant>DBX_CMP_ASC</constant> - ascending order
</simpara>
</listitem>
<listitem>
<simpara>
<constant>DBX_CMP_DESC</constant> - descending order
</simpara>
</listitem>
</itemizedlist>
and the preferred comparison type:
<itemizedlist>
<listitem>
<simpara>
<constant>DBX_CMP_NATIVE</constant> - no type conversion
</simpara>
</listitem>
<listitem>
<simpara>
<constant>DBX_CMP_TEXT</constant> - compare items as strings
</simpara>
</listitem>
<listitem>
<simpara>
<constant>DBX_CMP_NUMBER</constant> - compare items numerically
</simpara>
</listitem>
</itemizedlist>
One of the direction and one of the type constant can be combined with
bitwise OR operator (|). The default value for the
<parameter>flags</parameter> parameter is <constant>DBX_CMP_ASC</constant>
| <constant>DBX_CMP_NATIVE</constant>.
</para>
<example>
<title><function>dbx_compare</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
function user_re_order($a, $b)
{
$rv = dbx_compare($a, $b, "parentid", DBX_CMP_DESC);
if (!$rv) {
$rv = dbx_compare($a, $b, "id", DBX_CMP_NUMBER);
}
return $rv;
}
$link = dbx_connect(DBX_ODBC, "", "db", "username", "password")
or die("Could not connect");
$result = dbx_query($link, "SELECT id, parentid, description FROM table ORDER BY id");
// data in $result is now ordered by id
dbx_sort($result, "user_re_order");
// date in $result is now ordered by parentid (descending), then by id
dbx_close($link);
?>
]]>
</programlisting>
</example>
<para>
See also <function>dbx_sort</function>.
</para>
</refsect1>
</refentry>
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