Re: RA with MV attributes

David wrote:
> paul c wrote:
> ...

>>I do think that once one has a definition it is important to proceed to
>>positioning it in the scheme of things, for example is this a physical
>>approach for storing two relations in one or is it an attempt to promote
>>three-valued logic or is it something else?

I could entertain this if the motive were to formalize a physical storage scheme. But I don't see anything logical about presenting to a user the inference that fred and bill own an empty set of cars that are green, especially if the user could then project away the Cars attribute and conclude that they do own a green car or cars. (That seems like using the empty set to achieve Codd's connection trap.)

p Received on Fri Jan 19 2007 - 12:01:06 CET