Message-ID: <45D46196.2090003@archonet.com>
Date: Thu, 15 Feb 2007 13:35:18 +0000
From: Richard Huxton <dev@archonet.com>
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To: Walter Cruz <walter.php@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: "for SELECT DISTINCT, ORDER BY expressions must appear
	in select list" - is that the standart or a limitation of postgresql?
References: <32cabba0702150319v427d5a25s9a6c7f851576baa2@mail.gmail.com>
In-Reply-To: <32cabba0702150319v427d5a25s9a6c7f851576baa2@mail.gmail.com>
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Walter Cruz wrote:
> 
> SELECT distinct name from test order by number
> 
> (well, I think that que query doesn't make any sense, but raises the 
> error :) )
> 
> The error: ERROR:  for SELECT DISTINCT, ORDER BY expressions must
> appear in select list is due to a standart implementarion or a design
> decision of postgres?

I think ORDER BY is defined to take place after DISTINCT, which means 
there is no meaningful "number" for it to order by. You could 
arbitrarily choose the first number encountered, but I can't see what 
sense it would make to order by them.

-- 
   Richard Huxton
   Archonet Ltd