Total in the Grid

function pre_render($data)
{
    $rows = $_GET["jqgrid_page"] * $_GET["rows"];
    $sidx = $_GET['sidx']; // get index row - i.e. user click to sort
    $sord = $_GET['sord']; // get the direction

    // same sql as in select_command
    $rs = mysql_fetch_assoc(mysql_query("SELECT SUM(vlr_cust_total) as s FROM (SELECT vlr_cust_total FROM cdr ORDER BY $sidx $sord LIMIT $rows) AS tmp"));
    foreach($data["params"] as &$d)
    {
        $d["running_total"] = $rs["s"];
    }
}