From: Jean-Luc Lachance <jllachan@sympatico.ca>
To: Andrew Perrin <clists@perrin.socsci.unc.edu>
Cc: pgsql-sql@postgresql.org
Subject: Re: Complicated "group by" question
Date: Wed, 25 Aug 2004 13:54:15 -0400
Message-ID: <412CD247.5020706@sympatico.ca> (raw)
In-Reply-To: <Pine.LNX.4.53.0408251300580.20106@perrin.socsci.unc.edu>
References: <Pine.LNX.4.53.0408251300580.20106@perrin.socsci.unc.edu>
Andrew,
If assing is not a many to many relation,
why did you not fold accept_id into assign?
Any way, here is the query you need:
select assign.reviewer_id, ss.max_assign_date,
accept.assign_id, accept.accept_id
from (
select reviewer_id, max( assign_date) as max_assign_date
from assign group by reviewer_id) as ss, assign, accept
where ss.reviewer_id = assign.reviewer_id
and ss.max_assign_date = assign.assign_date
and assign.assign_id = accept.assign_id;
Andrew Perrin wrote:
> I have a table of people ("reviewers"), a table of review assignments
> ("assign"), and a table of review acceptances ("accept"). I would like to
> be able to write a query to return the latest (e.g., max(assign_date))
> assignment for each reviewer, plus the acc_id field from "accept". I
> think I should be able to do this with a GROUP BY clause, but am having no
> luck.
>
> Table structure:
>
> reviewers assign accept
> -----------------------------------------
> reviewer_id assign_id accept_id
> reviewer_id assign_id
> ... assign_date
> ... ...
>
>
> Thanks for any guidance.
>
> 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
>
>
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To: pgsql-sql@postgresql.org
Cc: jllachan@sympatico.ca, clists@perrin.socsci.unc.edu
Subject: Re: Complicated "group by" question
In-Reply-To: <412CD247.5020706@sympatico.ca>
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