Re: Multiple-Attribute Keys and 1NF
Date: Tue, 28 Aug 2007 19:05:33 GMT
>> JOG wrote: >>> On Aug 28, 5:43 pm, Bob Badour <bbad..._at_pei.sympatico.ca> wrote: >>>> JOG wrote: >>>>> On Aug 28, 5:05 pm, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:...
>> I don't recall suggesting anything about sets--just a domain that has a >> distinct value that means "green and yellow".
> Okay, sure. But then to be able to query for green and yellow
> individually one must employ a further relation encoding two more
> propositions that state "'Green and yellow' contains 'Green'" and that
> "'Green and yellow' contains 'Yellow'" respectively. One then has a
> schema with two domains - one for the composites and one for
> individual colours (which is what I was inferring when I initially
> said a new one was being added).
I took Bob B to mean something else, eg., allowing the colour purple doesn't require an app to record what primary colours purple is usually fashioned from (maybe they're green and blue, I forget, but which they are doesn't change the point).
p Received on Tue Aug 28 2007 - 21:05:33 CEST