Re: more closed-world chatter

On 3 mai, 17:26, "David Cressey" <cresse..._at_verizon.net> wrote:
> "Cimode" <cim..._at_hotmail.com> wrote in message
>
> news:1178200219.598399.84110_at_o5g2000hsb.googlegroups.com...
>
>
>
> > On May 2, 10:13 pm, paul c <toledobythe..._at_oohay.ac> wrote:
>
> > > If I have a domain of items consisting of the values "a" and "b" and a
> > > domain of item prices consisting of the values "1" and "2" and an empty
> > > relation {ItemID, Price} known by the relvar name "Items", I take it
> > > that the logical complement of "Items" has four tuples - loosely,
> > > <a,1>,<a,2>,<b,1>,<b,2>.
>
> > > If I select from Items where Price = 3, should a dbms answer with an
> > > empty relation or should it take exception, such as "illegal question"?
> > I would like to point out two comments triggered by your question.
>
> > A TRDBMS should detect disjoint types are to be determined at compile
> > time. In my perspective, there should be no exception because there
> > should be no execution in the first place. That of course, in a
> > purely empirical perspective.
>
> I am not convinced. Why should the binding happen at compile time.
> Couldn't a TRDBMS be extended to allow dynamic typing?
I am not sure what you mean. Typing here is not as relevant as the way it would be represented. The argument about a TRDBMS is not as much about logical model then a computing model and interval based representation of sets (and therefore some of their properties such as disjointness). Received on Thu May 03 2007 - 18:45:22 CEST