Re: (un)grouping question

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Rhys Stewart <rhys(dot)stewart(at)gmail(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: (un)grouping question
Date: 2008-01-21 19:50:11
Message-ID: 1200945011.10057.516.camel@dogma.ljc.laika.com
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On Mon, 2008-01-21 at 14:25 -0500, Rhys Stewart wrote:
> ok, let me clarify, dont want to remove them just want them changed
> but need to keep the uid. However, I would like just one somevalue to
> remain the same. so for example, uids, 2,4 and 8 have somevalue 44,
> after i would like 2 to remain 44 but uids 4 and 8 would be changed.

Can you explain why you're trying to do this? It's a very unusual
requirement.

That being said, the query would look something like this:

(SELECT MIN(uid) AS uid, somevalue FROM mytable GROUP BY somevalue)
UNION
(SELECT uid, somevalue + random() AS somevalue
FROM mytable WHERE uid NOT IN
(SELECT MIN(uid)
FROM mytable GROUP by somevalue)

Disclaimer: I haven't actually tested this query, but it looks about
right.

Regards,
Jeff Davis

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