function get_open_balance($supplier_id, $to)
{
    if($to)
        $to = date2sql($to);

        $sql = "SELECT SUM(IF(t.type = ".ST_SUPPINVOICE." OR (t.type IN (".ST_JOURNAL." , ".ST_BANKDEPOSIT.") AND t.ov_amount>0),
                        -abs(t.ov_amount + t.ov_gst + t.ov_discount), 0)) AS charges,";

 $sql .= "SUM(IF(t.type != ".ST_SUPPINVOICE." AND NOT(t.type IN (".ST_JOURNAL." , ".ST_BANKDEPOSIT.") AND t.ov_amount>0),
                        abs(t.ov_amount + t.ov_gst + t.ov_discount) * -1, 0)) AS credits,";

     $sql .= "SUM(IF(t.type != ".ST_SUPPINVOICE." AND NOT(t.type IN (".ST_JOURNAL." , ".ST_BANKDEPOSIT.")), t.alloc * -1, t.alloc)) AS Allocated,";

     $sql .=    "SUM(IF(t.type = ".ST_SUPPINVOICE.", 1, -1) *
             (abs(t.ov_amount + t.ov_gst + t.ov_discount) - abs(t.alloc))) AS OutStanding
        FROM ".TB_PREF."supp_trans t
        WHERE t.supplier_id = ".db_escape($supplier_id);
    if ($to)
        $sql .= " AND t.tran_date < '$to'";
    $sql .= " GROUP BY supplier_id";

    $result = db_query($sql,"No transactions were returned");
    return db_fetch($result);
}