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Date: Sun, 13 May 2007 03:49:24 -0500
From: "=?ISO-8859-1?Q?Rodrigo_De_Le=F3n?=" <rdeleonp@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: Funny date-sorting task
In-Reply-To: <5.2.1.1.0.20070512231137.042f88d0@pop6.sympatico.ca>
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On 5/12/07, Frank Bax <fbax@sympatico.ca> wrote:
> At 07:40 PM 5/12/07, Andreas wrote:
> >I've got a stack of tasks to show in a list.
> >Every task has a timestamp  X  that may be NULL or a date. It contains the
> >date when this tasks should be done.
> >Sometimes it has date and the time-part, too.
> >
> >
> >The list should be like this:
> >1)   X  sometime today should come first in ascending time order.
> >2)   X  in the past should show up after (1) in descending order so that
> >not so long back dates come first
> >3)   X  =  NULL
> >4)   X sometime in the future
> >
> >Could you provide a clever solution?
>
>
> ORDER BY CASE WHEN X=today THEN 1 ELSE
> CASE WHEN X<today THEN 2 ELSE
> CASE WHEN X IS NULL THEN 3 ELSE
> CASE WHEN X>today THEN 4 ELSE 5 END END END END

Less verbose:

ORDER BY CASE
WHEN x = today THEN 1
WHEN x < today THEN 2
WHEN x IS NULL THEN 3
WHEN x > today THEN 4
ELSE 5
END