Re: Does Codd's view of a relational database differ from that of Date & Darwin? [M.Gittens]
From: Paul <paul_at_test.com>
Date: Sun, 05 Jun 2005 00:47:26 +0100
Message-ID: <42a23d8f$0$21790$ed2619ec_at_ptn-nntp-reader01.plus.net>
Date: Sun, 05 Jun 2005 00:47:26 +0100
Message-ID: <42a23d8f$0$21790$ed2619ec_at_ptn-nntp-reader01.plus.net>
Marshall Spight wrote:
>>Anything that can be modeled with [nulls]
>>can also be modeled without them, and to the extent that they
>>are convenient this is mostly due to the fact that the possibilities for
>>user-defined domains were too restricted.
>
> That statement surprises me. What about outer join?
Outer joins are really just a syntactic shorthand for a normal join and some kind of union. If you weren't allowed NULLs you could still have a kind of outer join, you'd just have to specify default values for the columns to be used instead of a NULL.
Paull Received on Sun Jun 05 2005 - 01:47:26 CEST