Re: So what's null then if it's not nothing?
Date: Thu, 17 Nov 2005 22:39:50 GMT
Message-ID: <WE7ff.9702$2y.5831_at_newsread2.news.atl.earthlink.net>
"David Portas" <REMOVE_BEFORE_REPLYING_dportas_at_acm.org> wrote in message news:1132246841.936501.150760_at_o13g2000cwo.googlegroups.com...
> Not at all the same thing because nulls violate the Information
> Principle, which is a foundation of RM. Nulls as formulated in SQL also
> create logical problems that are very hard to solve - at least SQL
> hasn't succeeded in solving them very satisfactorily.
Not according to Codd.
> RM does not prohibit such questions. If it is more natural to give some
> answer then the user can demand such an answer. The user can decide
> what he wants to see in the case of a dog with colour or a dog without
> colour. I would challenge your implication that users find nulls"more
> natural". I bet most DBMS users wouldn't do a very good job of
> explaining what a null is. In fact in many database projects the
> developers go to a lot of trouble to hide nulls from regular users.
And, in the real world, the user frequently deals with dogs that might or
might not have color,
and doesn't care about that.
Received on Thu Nov 17 2005 - 23:39:50 CET