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To: Andrew Perrin <clists@perrin.socsci.unc.edu>
Cc: pgsql-sql@postgresql.org
Subject: Re: LIMIT within UNION? 
In-reply-to: <Pine.LNX.4.21.0209121454540.32000-100000@perrin.socsci.unc.edu> 
References: <Pine.LNX.4.21.0209121454540.32000-100000@perrin.socsci.unc.edu>
Comments: In-reply-to Andrew Perrin <clists@perrin.socsci.unc.edu>
	message dated "Thu, 12 Sep 2002 15:11:45 -0400"
Date: Thu, 12 Sep 2002 15:34:07 -0400
Message-ID: <9272.1031859247@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
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Andrew Perrin <clists@perrin.socsci.unc.edu> writes:
> SELECT ... FROM participants
> WHERE typenr=1 AND <eligibility>
> UNION
> SELECT ... FROM participants
> WHERE typenr=2 LIMIT 172
> ORDER BY zip;

I think you need

SELECT * FROM
(
SELECT ... FROM participants
WHERE typenr=1 AND <eligibility>
UNION
(SELECT ... FROM participants
WHERE typenr=2 LIMIT 172)
) ss
ORDER BY zip;

Not sure if the inner set of parens is essential, but it might be.
The outer SELECT superstructure is definitely necessary to give a
place to hang the ORDER BY on.

			regards, tom lane