Re: object algebra

From: Neo <neo55592_at_hotmail.com>
Date: 24 Feb 2004 22:36:01 -0800
Message-ID: <4b45d3ad.0402242236.68586a94@posting.google.com>

> > And when it doesn't, RDM needs NULLs, as Codd has correctly recognized.
>
> Codd believed that incorrectly, as Date implies.

Date is correct in that there is something inherently wrong with a model that allows NULLs.

Codd is correct in that NULLs are an integral part of RDM.

NULLs are integral part of RDM because RDM is slightly flawed.

When one substitutes "Not applicable" for NULL, the flaw is only partially masked. NULLs kill closure. How does substituting "Not applicable" for NULL significantly enhance closure? Received on Wed Feb 25 2004 - 00:36:01 CST