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  • delete from 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=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)
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  • 原文地址:https://www.cnblogs.com/cxd4321/p/2117434.html
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