From: | Bruno Wolff III <bruno(at)wolff(dot)to> |
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To: | charlie clark <charlie(at)begeistert(dot)org> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: How do I change sort order behavious with nulls |
Date: | 2005-02-19 18:01:07 |
Message-ID: | 20050219180107.GB15226@wolff.to |
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Lists: | pgsql-general |
On Sat, Feb 19, 2005 at 18:04:32 +0100,
charlie clark <charlie(at)begeistert(dot)org> wrote:
> Dear list,
>
> is there a simple way to change the way ORDER BY works on columns with
> NULLs? I can understand the need for default behaviour but there must be
> cases when this is undesirable. I have such a query with the NULLs arising
> as the result of an OUTER JOIN and I would like to ORDER BY DESC with
> NULLs treated as <= 0. I've already tried a few things but nothing's
> working so far.
Presumably what you mean is that you want NULLs to be output last when
doing a descending order by.
You can do this using ORDER BY whatever IS NULL ASC, whatever DESC .
If you really mean you want to treat them as less than or equal to
0, then you can pick such a value and use coalesce to change NULLs
to that value in the ORDER BY clause.
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