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

1. update tb_User 
2. set pass='' 
3. from tb_User usr 
4. inner join tb_Address addr on usr.nAddressFK = addr.nAddressID 
5. 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

1. UPDATE mem_world AS mw1 INNER JOIN mem_world   AS   mw2   
2. ON   mw1.parentid = mw2.wid  
3. SET mw1.level = mw2.level   
4. WHERE mw2.baseid = 107   
5. AND   mw2.parentid = 0   
6. 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)

 

 

/*-------------------------------------------------------------------*/
DROP TABLE IF EXISTS temp;
CREATE TABLE `temp` (
  `id` VARCHAR(64) CHARACTER SET utf8 NOT NULL DEFAULT '',
  `min_price` DECIMAL(10,2) NOT NULL,
  `max_price` DECIMAL(10,2) NOT NULL,
  `price_count` INT(11) NOT NULL DEFAULT '0'
) ENGINE=INNODB;
/**/
INSERT INTO temp (id,min_price,max_price,price_count) SELECT product_id,MAX(price),MIN(price),COUNT(*) FROM product_price GROUP BY product_id;

/*修改成功*/
UPDATE product P INNER JOIN temp T ON P.id=T.id SET P.min_price=T.min_price,P.max_price=T.max_price,P.price_count=T.price_count;

/*删除临时表*/
DROP TABLE IF EXISTS temp;
/*--------------------------------------------------------------------*/   

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