关于用OR删除

Question

DELETE OBJ_M_ACTORLINK
  WHERE OBJ_M_ACTOR.M_ACTOR_N_ID not in(1,2);DELETE OBJ_M_ACTORLINK
  WHERE OBJ_M_ACTOR.M_ACTOR_N_ID  <> 1 OR OBJ_M_ACTOR.M_ACTOR_N_ID  <> 2;

Answer 1

DELETE from OBJ_M_ACTORLINK
  WHERE OBJ_M_ACTOR.M_ACTOR_N_ID  not in (1,2);

Answer 2

上面的语句可以实现如下:
DELETE OBJ_M_ACTORLINK
  WHERE to_char(OBJ_M_ACTOR.M_ACTOR_N_ID) not in ('1','2');
而下面的不能,1,2记录将被删除
DELETE OBJ_M_ACTORLINK
  WHERE OBJ_M_ACTOR.M_ACTOR_N_ID  <> 1 OR OBJ_M_ACTOR.M_ACTOR_N_ID  <> 2;