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