请教复杂SQL语句??谢谢

Question

表 a 
order_id(自增)    order_code             order_state(状态)
----------------------------------------------------------------------
1                       2005000012345       a
2                       2005000045678       t  
3                       2005000057892       t表 b
id(自增)      order_id       order_state
-------------------------------------------------------------
1                   1                     t
2                   1                     c
3                   1                     a
4                   2                     a
5                   2                     t问题：如何同时把两张表中的 t 修改为 e

Answer 1

何謂同時修改？用兩個修改語句不行嗎？--一、必須先改表b
UPDATE b SET order_state='e' where 
(order_id,order_state) in 
(select b.order_id,b.order_state from a,b 
where b.order_state='t' and a.order_id=b.order_id and 
a.order_state=b.order_state);--可以去掉a.order_state=b.order_state條件
--二、再改表a
UPDATE a SET order_state='e' where order_state='t'

Answer 2

我的注釋中有點小問題，應為：--如果兩表中的order_id加order_state不是唯一的，則不能去掉a.order_state=b.order_state條件