From: Weimao Ke <wke@indiana.edu>
To: Daniel CAUNE <d.caune@free.fr>
Cc: pgsql-sql@postgresql.org
Subject: Re: pgsql aggregate: conditional max
Date: Sun, 12 Mar 2006 14:59:19 -0500
Message-ID: <44147D97.5050301@indiana.edu> (raw)
In-Reply-To: <0IW0005WSPTDIA40@VL-MH-MR002.ip.videotron.ca>
References: <0IW0005WSPTDIA40@VL-MH-MR002.ip.videotron.ca>
Daniel CAUNE wrote:
> SELECT aid, cat
>
> FROM table, (
> SELECT aid, max(weight) as weight
> FROM table
> GROUP BY aid) AS tablemaxweight
> WHERE table.aid = tablemaxweight.aid
> AND table.weight = tablemaxweight.aid;
>
>There is a limit case you don't specify how to deal with, when two or more categories have the same maximum weight. The query I wrote retrieves all the categories that have the maximum weight, but perhaps you just want one per aid.
>
>
Yes, this will introduce duplicates. Yet it is not too difficult to
select only one for each aid from the results. Thank you!
Weimao
>--
>Daniel
>
>
>
>
--
All best,
Weimao
Weimao Ke
Indiana University Bloomington
School of Library and Information Science
http://ella.slis.indiana.edu/~wke
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To: pgsql-sql@postgresql.org
Cc: wke@indiana.edu, d.caune@free.fr
Subject: Re: pgsql aggregate: conditional max
In-Reply-To: <44147D97.5050301@indiana.edu>
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