查询优化

尽量先过滤数据再进行表连接，

例如：select a from tblUser inner join tblShop on tblUser.id=tblShop.id

　　　　　　　　　　　　　　inner join tblThing on tblUser.id=tblThing.id

　　 where tblUser.id=4

改为 select a

　　 from (select * from tbluser where tbluser.id=4) as tblUser

      inner join tblShop on tblUser.id=tblShop.id

　　inner join tblThing on tblUser.id=tblThing.id

MSDN: http://172.18.14.131/LockSmith/Default.aspx

Great site

查询优化