SQL语句Update和Delete时表关联的写法
Update XXX set XXX where 这种写法⼤家肯定都知道，才发现update和delete居然⽀持多表关联的update⽅式，这个在表间关联来做更新和删除操作⾮常有⽤.
update的格式是
update t1 set t1.name=’Liu’ from t1 inner join t2 on t1.id = t2.tid
【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
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的格式是
sql中update什么意思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
pe 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
pe 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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