oracle触发器实现

create or replace trigger AddTrainDayMove
  before insert on train_day_move
  for each row
declare
  t_month_move      integer;
  t_after_make_move integer;
  c_month           int;
  c_day             int;
begin

  select count(*)
    into c_day
    from train_day_move
   where month = :new.month
     and year = :new.year
     and train_id = :new.train_id;
  if c_day > 0 then
    /*机车当月走行*/
    select sum(t.day_move)
      into t_month_move
      from train_day_move t
     where t.month = :new.month
       and t.year = :new.year
       and t.train_id = :new.train_id;
  
    /*机车新造走行*/
    select t.after_make_move
      into t_after_make_move
      from train_day_move t
     where t.train_id = :new.train_id