declare   cursor readflow_cur is  select * from od_readflow t where t.flowid is null;  l_emp od_readflow%rowtype;begin  open readflow_cur;   loop       fetch readflow_cur into l_emp;       exit when readflow_cur%notfound;       update od_readflow r set r.flowid = (select d.flow_id from od_docinfo d where d.bill_id = l_emp.flowinstanceid) where r.readid = l_emp.readid;    end loop;   commit;   close readflow_cur;end;