Oracle 触发器

create or replace trigger T_EXAM_OTHERS_SOCRE_NUM_ID
  before insert on t_exam_others_score 
  for each row
declare
  ID_ urp_exam.t_exam_others_score.num_id%type;
begin
  select SEQ_T_EXAM_OTHERS_SCORE.NEXTVAL INTO ID_ FROM DUAL;
  :NEW.NUM_ID := ID_;
end T_EXAM_OTHERS_SOCRE_NUM_ID;