not exists不能仅仅理解为差集

要看以谁为主表，

见如下示例，同样的表，主表不一样，结果不一样：

?

?

select * from [left]  lwhere not exists (select * from [right] rwhere l.name=r.name)-------------------------------下面这个例子充分说明,not exists不能单单理解为差集select * from [right]  rwhere not exists (select * from [left] lwhere l.name=r.name)

?

?

?

?

?

?