今天写程序时写了两个LeftJoin但是返回结果集是一样的,不知为何~大家看一下~很简单的一个例子select Distinct * from A
left join B on A.aaa=B.aaa (aaa为关联字段)
left join C on B.bbb=C.bbb (bbb为关联字段)
where A.ID='12'select Distinct * from A
left join (B left join C on B.bbb=C.bbb) on A.aaa=B.aaa
where A.ID='12'
left join B on A.aaa=B.aaa (aaa为关联字段)
left join C on B.bbb=C.bbb (bbb为关联字段)
where A.ID='12'select Distinct * from A
left join (B left join C on B.bbb=C.bbb) on A.aaa=B.aaa
where A.ID='12'
解决方案 »
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