"Pascal Tufenkji" <ptufenkji(at)usj(dot)edu(dot)lb> writes:
> I understand the fact that "the inner query is executed before the outer
> query and the inner query doesn't even know about the outer query."
> But why the following query can be executed, although the inner query is
> using the outer query.
> Aren't we here using the same concept ?
It's not that inner queries can't refer to outer queries. When they do it's
called a "correlated subquery" and it has to be executed once for every row of
the outer query.
It's that queries on one side of a join can't refer to tables on the other
side of the join.
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