From: Richard Broersma Jr <rabroersma@yahoo.com>
To: Mike Diehl <jdiehl@sandia.gov>
To: SQL Postgresql List <pgsql-sql@postgresql.org>
Subject: Re: Problem with phone list.
Date: Wed, 15 Aug 2007 14:00:05 -0700 (PDT)
Message-ID: <846214.97432.qm@web31807.mail.mud.yahoo.com> (raw)
In-Reply-To: <200708151428.17740.jdiehl@sandia.gov>
--- Mike Diehl <jdiehl@sandia.gov> wrote:
> I've qot a problem I need to solve. I'm sure it's pretty simple; I just can't
> seem to get it, so here goes...
>
> I've got a table, actually a view that joins 3 tables, that contains a phone
> number, a unique id, and a call duration.
>
> The phone number has duplicates in it but the unique id is unique.
>
> I need to get a list of distinct phone numbers and the coorisponding largest
> call duration.
>
> I've got the idea that this should be a self-join on phone number where
> a.id<>b.id, but I just can't seem to get the max duration.
SELECT phone_number, max( duration ) as max_duration
FROM your_view
GROUP BY phone_number;
if you need the unique Id also,
SELECT DISTINCT ON ( phone_number ) id, phone_number, duration
FROM your_view
ORDER BY duration desc;
or
SELECT V1.id, V1.phone_number, V1.duration
FROM your_view AS V1
INNER JOIN ( SELECT phone_number, max( duration )
FROM your_view
GROUP BY phone_number ) AS V2( phone_number, duration )
ON (V1.phone_number, V1.duration) = (V2.phone_number, V2.duration);
Regards,
Richard Broersma Jr.
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To: pgsql-sql@postgresql.org
Cc: rabroersma@yahoo.com, jdiehl@sandia.gov
Subject: Re: Problem with phone list.
In-Reply-To: <846214.97432.qm@web31807.mail.mud.yahoo.com>
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