php-doc-en/reference/dbx/functions/dbx-compare.xml

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<refentry xml:id="function.dbx-compare" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>dbx_compare</refname>
  <refpurpose>Compare two rows for sorting purposes</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <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><initializer>DBX_CMP_ASC | DBX_CMP_NATIVE</initializer></methodparam>
  </methodsynopsis>
  <para>
   <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>
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>row_a</parameter></term>
     <listitem>
      <para>
       First row
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>row_b</parameter></term>
     <listitem>
      <para>
       Second row
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>column_key</parameter></term>
     <listitem>
      <para>
       The compared column
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>flags</parameter></term>
     <listitem>
      <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 (|).
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   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>.
  </para>
 </refsect1>
 <refsect1 role="examples">
  &reftitle.examples;
  <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>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>dbx_sort</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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