Question

SQL数据库把a表的字段1.字段2 放到b表的字段1.字段2中去2个表的字段1 字段2列名都一样

UPDATE METERDEVICE
SET roomid =
(SELECT roomid
FROM ROOMINFO
WHERE (roomname = meterdevice.roomdm))
UPDATE METERDEVICE
SET roomdm =
(SELECT roomdm
FROM ROOMINFO
WHERE (meterdevice.roomid =ROOMINFO.roomid))
z执行后没有变化。。。

Answer 1

很绕,绕得有些晕
更新:
update b set 字段2 = (select 字段2 from a where a.字段1 = b.字段1)
其实你用不着更新,
b的字段2可以省
select b.字段1 ,a.字段2 from a inner join b on a.字段1=b.字段1