SQL语句 Update和Delete时表关联的写法

Update XXX set XXX where 这种写法大家肯定都知道，才发现update和delete居然支持多表关联的update方式，这个在表间关联来做更新和删除操作非常有用.

update的格式是

update t1 set t1.name=’Liu’ from t1 inner join t2 on t1.id = t2.tid 
【列子: 】
Sql代码
update tb_User
set pass=''
from tb_User usr
inner join tb_Address addr on usr.nAddressFK = addr.nAddressID
where usr.id=123

update tb_User
set pass=''
from tb_User usr
inner join tb_Address addr on usr.nAddressFK = addr.nAddressID

where usr.id=123

MYSQL，ACCESS 写法如下:
Sql代码
UPDATE mem_world AS mw1 INNER JOIN mem_world AS mw2
ON mw1.parentid = mw2.wid
SET mw1.level = mw2.level
WHERE mw2.baseid = 107
AND mw2.parentid = 0
AND mw2.size > 1;

UPDATE mem_world AS mw1 INNER JOIN mem_world AS mw2
ON mw1.parentid = mw2.wid
SET mw1.level = mw2.level
WHERE mw2.baseid = 107
AND mw2.parentid = 0
AND mw2.size > 1;

on是表连接的筛选条件
就是说，表连接后，会产生一个类似于临时的视图这么一个东西
where是从这个临时的视图中筛选数据的
所以，你首先要搞清，你的所谓的2个条件属于哪一种




delete的格式是
delete from t1 from t1 inner join t2 on t1.id = t2.tid

注意蓝色部分。

mysql:


Sql代码
DELETE mwb FROM mem_world_building AS mwb INNER JOIN mem_world AS mw
ON mwb.wid = mw.wid
where mw.type between 11 and 15
and baseid = 107
and mw.parentid <> 0
and mw.size > 1;

DELETE mwb FROM mem_world_building AS mwb INNER JOIN mem_world AS mw
ON mwb.wid = mw.wid
where mw.type between 11 and 15
and baseid = 107
and mw.parentid <> 0
and mw.size > 1;
下面是ORACLE的:


Sql代码
DELETE TABLE1 where exists ( select 1 from table2 where and table1.khid=table2.khid and FWDWID=8);

DELETE TABLE1 where exists ( select 1 from table2 where and table1.khid=table2.khid and FWDWID=8);



Sql代码
DELETE TABLE1 where KHID exists ( select KHID from table2 where FWDWID=8)

DELETE TABLE1 where KHID exists ( select KHID from table2 where FWDWID=8)