Re: Natural keys vs Aritficial Keys

On May 29, 1:27 am, paul c <toledobythe..._at_oohay.ac> wrote:
> Walter Mitty wrote:
>
> ...
>
> > I don't understand how your response differs from my earlier comment. I
> > think I said that a variable that records a set of values (which I called
> > the first case) has a variable cardinality.
> > The second case, a set of variables is not, if I read it correctly, a
> > variable.
>
> I don't either. Relations are addressable by their content. Relations
> can be constrained to a single tuple.

It seems odd to bring integrity constraints into a discussion which mainly concerns the distinction between variable and value.

Some relation values have a single tuple and some don't. Your comment is like saying "integers can be constrained to be greater than 10". Out of context it's a strange thing to say. What is your point exactly?

> If he (or anybody else) is
> proposing that a tuple programming and user interface is superior to a
> relation interface then they will have to go quite a few steps beyond
> addressing, they will have to suggest some tuple operators and why they
> would be better, more useful, et cetera. Would such operators replace
> relational ones or just augment them? If the latter, why would you need
> both?

Who is proposing any of that? Am I "he" in the above? Received on Fri May 29 2009 - 04:01:59 CEST