| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Mike Christensen <mike(at)kitchenpc(dot)com> |
| Cc: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: What's wrong with this query? |
| Date: | 2010-09-22 14:28:41 |
| Message-ID: | 24836.1285165721@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Mike Christensen <mike(at)kitchenpc(dot)com> writes:
> So are you saying that a JOIN can only refer to itself and the last
> table on the FROM list?
Um, I think you've got the wrong mental model of the syntax. JOIN
is a binary operation between two tables:
tab1 JOIN tab2 ON some-condition-involving-tab1-and-tab2-only
You can nest these critters (ie, tab1 or tab2 could itself be a
JOIN construct), and you can write them as elements of a comma-separated
FROM list. But the ON condition can never refer to anything outside
its JOIN construct.
regards, tom lane
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