Re: grouping in tuple relational calculus
From: Paul <paul_at_test.com>
Date: Thu, 17 Feb 2005 00:39:00 +0000
Message-ID: <4213e7b7$0$53482$ed2619ec_at_ptn-nntp-reader03.plus.net>
Date: Thu, 17 Feb 2005 00:39:00 +0000
Message-ID: <4213e7b7$0$53482$ed2619ec_at_ptn-nntp-reader03.plus.net>
Mikito Harakiri wrote:
> Speaking of aggregates, I always wondered why some aggregates are
> expressable by standard means (min, max can be expressed as antijoins),
> while the others aren't (sum).
I guess that min and max only require an ordering, which is a more
fundamental concept than addition, which is required for sum.
And min and max work on all domains that have an ordering operator
Paul. Received on Thu Feb 17 2005 - 01:39:00 CET