Re: Codd's Information Principle
From: <compdb_at_hotmail.com>
Date: Sun, 1 Nov 2009 15:36:31 -0800 (PST)
Message-ID: <b8e7a4ce-4289-43c9-abe8-32b358a26f40_at_c3g2000yqd.googlegroups.com>
Date: Sun, 1 Nov 2009 15:36:31 -0800 (PST)
Message-ID: <b8e7a4ce-4289-43c9-abe8-32b358a26f40_at_c3g2000yqd.googlegroups.com>
On Oct 31, 9:03 am, "Mr. Scott" <do_not_re..._at_noone.com> wrote:
> A sentence is a well-formed formula with no free variables.
Yes, I was wrong.
> Are you saying that there is no point in defining constraints?
No, you can use them for all the things they are useful for.
(Support the user's understanding of the predicates,
help the designer improve the design,
help the dbms to prevent invalid states from user input errors,
help the dbms to optimize execution, etc.)
But they're not necessary for understanding, updating
or querying the database. The user just needs the predicates.
We'll just have to disagree about the rest.
philip Received on Mon Nov 02 2009 - 00:36:31 CET