create or replace trigger ia_sl
  before update on po_invoice
  referencing old as old_value new as new_value
  for each row
    
declare
cursor test_cursor is select ntaxmny, ia_bill_b.cbill_bid
               from ia_bill_b,
                    po_settlebill_b,
                    po_invoice_b,
                    ia_bill,
                    po_invoice
              where po_invoice.cinvoiceid = po_invoice_b.cinvoiceid
                and ia_bill_b.csourcebillitemid =
                    po_settlebill_b.csettlebill_bid
                and po_settlebill_b.cinvoice_bid = po_invoice_b.cinvoice_bid
                and ia_bill_b.cbillid = ia_bill.cbillid
                and ia_bill.bestimateflag = 'N'
                and po_invoice.cinvoiceid = :new_value.cinvoiceid;
begin

  for nx in test_cursor loop
    update ia_bill_b
       set vdef1 = nx.ntaxmny
     where ia_bill_b.cbill_bid = nx.cbill_bid;
  end loop;
END;