update和delete支持inner join的update方式

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=123update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 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)

 

--转自网络

转载于:https://www.cnblogs.com/AppleZhang/p/5754241.html