/includes/ajax_sort_clients.php

<?php
	$debug = 0; // only for testing and debugging, will break otherwise
	include("../mysql.php");
	$link = mysql_connect($mysqlhost, $mysqluser, $mysqlpass) or die("Could not connect to server");
	mysql_select_db($mysqldb) or die("Could not select database");
	parse_str($_POST['id'], $sortlist);
	$i = 0;
	foreach( $sortlist as $name => $array ) {
		foreach( $array as $key => $value ) {
			$i++;
			$update_sql = "UPDATE clients SET sort='" . $i . "' WHERE id='" . $value . "'";
			$update_query = mysql_query($update_sql) or die(mysql_error());
		}
	}
	if($debug) { var_dump($sortlist); }
?>