From: | The Hermit Hacker <scrappy(at)hub(dot)org> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | <pgsql-sql(at)postgresql(dot)org>, <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: LEFT JOIN ... |
Date: | 2001-06-18 18:26:41 |
Message-ID: | Pine.BSF.4.33.0106181525140.22744-100000@mobile.hub.org |
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Thread: | |
Lists: | pgsql-hackers pgsql-sql |
On Mon, 18 Jun 2001, Tom Lane wrote:
> The Hermit Hacker <scrappy(at)hub(dot)org> writes:
> > FROM note_links nl, notes n LEFT JOIN calendar c ON (n.nid = c.nid)
> > WHERE (n.type = 'A' OR n.type = 'N' OR n.type = 'H' OR n.type = 'C')
> > AND (nl.id = 15748 AND contact_lvl = 'company')
> > AND n.nid = nl.nid
> > ORDER BY start DESC;
>
> > Is there some way to write the above so that it evaluates:
> > first, so that it only has to do the LEFT JOIN on the *one* n.nid that is
> > returned, instead of the 86736 that are in the table?
>
> Try adding ... AND n.nid = 15748 ... to the WHERE. It's not very
> bright about making that sort of transitive-equality deduction for
> itself...
n.nid is the note id ... nl.id is the contact id ...
I'm trying to pull out all notes for the company with an id of 15748:
sepick=# select * from note_links where id = 15748;
nid | id | contact_lvl | owner
-------+-------+-------------+-------
84691 | 15748 | company | f
(1 row)
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