SQL中使用update inner join和delete inner join

Update

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inner join的update方式，这个在表间关联来做更新和删除操作非常有用.

列子:

 

Sql代码

update tb_User  

set pass=''   --此处pass前不要加 tb_User 别名usr

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

update的格式是

update t1 set t1.name=’Liu’ from t1 inner join t2 on t1.id = t2.tid

 

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

 

delete 语句也是类似

delete from t1 from t1 inner join t2 on t1.id = t2.tid

注意蓝色部分。

mysql:

 

Sql代码

1. DELETE mwb FROM   mem_world_building AS mwb INNER JOIN mem_world AS mw  
2. ON mwb.wid = mw.wid  
3. where mw.type between 11 and 15   
4. and baseid = 107   
5. and mw.parentid <> 0   
6. 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

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

 

Sql代码

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