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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Scott Marlowe <smarlowe@g2switchworks.com>
Cc: Greg Stark <gsstark@mit.edu>
Cc: Stephan Szabo <sszabo@megazone.bigpanda.com>
Cc: Rick Schumeyer <rschumeyer@ieee.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: pg, mysql comparison with "group by" clause
Date: Thu, 13 Oct 2005 14:49:37 -0400
Message-ID: <24789.1129229377@sss.pgh.pa.us> (raw)
In-Reply-To: <1129228672.29961.214.camel@state.g2switchworks.com>
References: <001001c5cea8$77cabc90$0300a8c0@dell8200>
	<20051011142658.C54076@megazone.bigpanda.com>
	<87br1u1jvq.fsf@stark.xeocode.com>
	<1129155875.29961.168.camel@state.g2switchworks.com>
	<87zmpez0au.fsf@stark.xeocode.com>
	<1129219046.29961.184.camel@state.g2switchworks.com>
	<878xwxi87h.fsf@stark.xeocode.com>
	<1129228672.29961.214.camel@state.g2switchworks.com>

>>>> In standard SQL you have to
>>>> write GROUP BY ... and list every single column you need from the master
>>>> table.

This thread seems to have gone off on a tangent that depends on the
assumption that the above is a correct statement.  It's not.  It *was*
true, in SQL92, but SQL99 lets you omit unnecessary GROUP BY columns.

The gripe against mysql, I think, is that they don't enforce the
conditions that guarantee the query will give a unique result.

The gripe against postgres is that we haven't implemented the SQL99
semantics yet.

			regards, tom lane

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