Re: Translating constraints to RM Terms

From: Paul <paul_at_test.com>
Date: Mon, 06 Jun 2005 16:13:07 +0100
Message-ID: <42a46804$0$41913$ed2619ec@ptn-nntp-reader03.plus.net>

Kenneth Downs wrote:
> Then I guess my question is restated, does the RM have anything to say about
> defining one column in terms of another?

you mean like a calculated column? Or a view?

> While the constraint is generally expressed and accepted as existing
> as a property of the *table*, is it not in fact a fundamental
> property of COLUMN A?

No, because if you drop column B, it become invalid. Maybe you could say it's a property of the set of columns {A, B}, but it seems to me cleaner and more useful to just say it's a table property.

Paul. Received on Mon Jun 06 2005 - 10:13:07 CDT