Re: LIMIT within UNION?

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От Andrew Perrin
Тема Re: LIMIT within UNION?
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Msg-id Pine.LNX.4.21.0209121540130.32000-100000@perrin.socsci.unc.edu
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Ответ на Re: LIMIT within UNION?  (Tom Lane <tgl@sss.pgh.pa.us>)
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Thanks! That did it.

The inner parens are necessary - without them the ORDER BY seems to be
parsed as part of the second subquery and is therefore a syntax error.

Best,
Andy

----------------------------------------------------------------------
Andrew J Perrin - http://www.unc.edu/~aperrin
Assistant Professor of Sociology, U of North Carolina, Chapel Hill
clists@perrin.socsci.unc.edu * andrew_perrin (at) unc.edu


On Thu, 12 Sep 2002, Tom Lane wrote:

> 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
> 



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