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Date: Wed, 19 Jun 2002 15:11:38 -0700 (PDT)
From: Stephan Szabo <sszabo@megazone23.bigpanda.com>
To: Michael Agbaglo <byteshifter@shifted-bytes.de>
Cc: <pgsql-sql@postgresql.org>
Subject: Re: syntax for access an alias in the where clause ?
In-Reply-To: <3D10C770.7040100@shifted-bytes.de>
Message-ID: <20020619150938.U78365-100000@megazone23.bigpanda.com>
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On Wed, 19 Jun 2002, Michael Agbaglo wrote:

> Hi !
>
> It's long ago since I used SQL :-)
>
> select [expression 1] as [alias 1], [expression 2] as [alias 2]
> where [alias 1] < [alias 2]
> order by [alias 2] - [alias 1]
>
> ---> ERROR:  Attribute '[alias 1]' not found
>
> I found a lot of 'select [expression] as' but I've never seen somebody
> accessing the alias ... Can't this be done ?

At least in postgres, no, because the where clause is processed before the
select list so the alias doesn't have meaning.  I believe the SQL spec
says no as well.