Re: Does Codd's view of a relational database differ from that ofDate& Darwin? [M.Gittens]
From: Paul <paul_at_test.com>
Date: Mon, 06 Jun 2005 16:23:13 +0100
Message-ID: <42a46a61$0$1696$ed2e19e4_at_ptn-nntp-reader04.plus.net>
>
> Nulls undermine the conceptual integrity of the Relational Model which
> is based in predicate logic.
>
> A tuple with nulls does not match to a logical proposition.
>
> This causes many problems. Some of them were pointed by Eric.
Date: Mon, 06 Jun 2005 16:23:13 +0100
Message-ID: <42a46a61$0$1696$ed2e19e4_at_ptn-nntp-reader04.plus.net>
Alfredo Novoa wrote:
>>I guess the other claim against NULLs is that they make things more >>complex and less intuitive, which is a more subjective point. You could >>argue that Darwen's method of avoiding NULLs is more complex that using >>NULLs in the first place.
>
> Nulls undermine the conceptual integrity of the Relational Model which
> is based in predicate logic.
>
> A tuple with nulls does not match to a logical proposition.
>
> This causes many problems. Some of them were pointed by Eric.
OK so basically the problem is with aggregates?
Why not say then that all aggregates that involve a NULL return NULL?
Paul. Received on Mon Jun 06 2005 - 17:23:13 CEST