Re: sub query

From: Christoph Haller <ch(at)rodos(dot)fzk(dot)de>
To: pgsql-sql(at)postgresql(dot)org
Cc: martinkuria(at)hotmail(dot)com
Subject: Re: sub query
Date: 2003-09-17 08:38:08
Message-ID: 3F681D6F.1E82CAFC@rodos.fzk.de
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> Hi I have this problem, when I try to run this query:
>
> SELECT MAX(d), host_position FROM (SELECT host_position,
> COUNT(host_position) as d FROM sss_host GROUP BY host_position) as e;
>
> am getting and ERROR: Attribute e.host_position must be GROUPed or
used in
> an aggregate function.
>
> Please to advice what could be the problem and how can I rewrite it to
work
> thanks in advance.
>
As the error message says: e.host_position must be GROUPed

so (supposing you want a one row result showing the maximum count)

SELECT MAX(e.d), e.host_position FROM (SELECT host_position,
COUNT(host_position) as d FROM sss_host GROUP BY host_position) as e
GROUP BY e.host_position ORDER BY 1 LIMIT 1;

should match your intentions.

Regards, Christoph

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