Re: object algebra
Date: Sat, 28 Feb 2004 23:58:58 GMT
Message-ID: <6X90c.81512$4o.104343_at_attbi_s52>
"Neo" <neo55592_at_hotmail.com> wrote in message news:4b45d3ad.0402281221.431f280_at_posting.google.com...
> > The above isn't a "patch for" nulls. What does "weaker relationship" mean,
> > though? I have no idea how to address that one.
>
> Given EyeColor = {red, brown, N/A} and the table:
> Person EyeColor
> ------ --------
> John N/A
> Mary N/A
>
> A query to find persons with equal eyeColor returns: John & Mary.
So, for example, if you asked the system to find all the pairs of people such that the eye color of all the eyes of the first person in the pair is equal to the eye color of all the eyes of the second person in the pair, then it darn well better return John and Mary, because they fit that description.
Marshall Received on Sun Feb 29 2004 - 00:58:58 CET