From: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
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To: | "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | "'pgsql-hackers(at)postgreSQL(dot)org'" <pgsql-hackers(at)postgreSQL(dot)org> |
Subject: | Re: [HACKERS] SELECT ... AS ... names in WHERE/GROUP BY/HAVIN G |
Date: | 1999-12-16 14:52:26 |
Message-ID: | 219F68D65015D011A8E000006F8590C603FDC1CE@sdexcsrv1.f000.d0188.sd.spardat.at |
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> Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> writes:
> > Informix and DB/2 allow column numbering in the group by clause.
>
> What do they do with
>
> SELECT foo AS bar FROM table GROUP BY bar
>
> What do they do if bar is the real name of another column in
> the table?
They don't allow labels, only numbers,
(SELECT foo AS bar FROM table GROUP BY 1)
In the special case where a label collides with a colname,
we need to use the colname, because that behavior is
ruled by the standard (since it doesn't allow a label).
The order by clause is the other way around.
DB Vendors probably disallow this syntax,
because the two different interpretations would be a bit awkward.
Best would of course be if the standard allowed labels in the
group by and where clause and take label before colname.
Andreas
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