触发器

create or replace trigger trg_ttank
  after update or delete  on ttank  
  for each row
declare
  tank_sum_amount int;
begin
  select sum(t.amount) into tank_sum_amount from ttank t where t.parentid = :new.parentid;
  update ttankarea t set t.amount = tank_sum_amount where t.objid = :new.parentid;
  dbms_output.put_line('ok');
end trg_ttank;