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Re: Subqueries
- From: Gregory Stark <stark(at)enterprisedb(dot)com>
- To: <ptufenkji(at)usj(dot)edu(dot)lb>
- Cc: "'Helio Campos Mello de Andrade'" <helio(dot)campos(at)gmail(dot)com>, <pgsql-sql(at)postgresql(dot)org>
- Subject: Re: Subqueries
- Date: Fri, 31 Oct 2008 10:58:40 +0000
- Message-id: <87hc6tghen.fsf@oxford.xeocode.com> <text/plain>
"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. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's On-Demand Production Tuning
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- Subqueries
- From: Pascal Tufenkji
- Re: Subqueries
- From: Helio Campos Mello de Andrade
- Re: Subqueries
- From: Pascal Tufenkji
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