Re: syntax for access an alias in the where clause ?

From: Jeff Eckermann <jeff_eckermann(at)yahoo(dot)com>
To: Michael Agbaglo <byteshifter(at)shifted-bytes(dot)de>, pgsql-sql(at)postgresql(dot)org
Subject: Re: syntax for access an alias in the where clause ?
Date: 2002-06-19 22:04:27
Message-ID: 20020619220427.58854.qmail@web20810.mail.yahoo.com
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The WHERE clause is evaluated before the SELECT list,
at which point the value of "[alias 1]" is not known.
You will need to use "[expression 1]" there instead.

ORDER BY is evaluated after the SELECT, so "[alias 1]"
can be used there with no problems.

--- Michael Agbaglo <byteshifter(at)shifted-bytes(dot)de>
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 ?
>
> M.
>
>
>
>
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