Re: Is relational theory irrelevant? (was Re: Dreaming About Redesigning SQL)

"Mikito Harakiri" <mikharakiri_at_iahu.com> wrote in message news:nsOsb.15$3D5.116_at_news.oracle.com...
>
> "Paul" <pbrazier_at_cosmos-uk.co.uk> wrote in message
> news:51d64140.0311130156.6c376b59_at_posting.google.com...
> > "Mikito Harakiri" <mikharakiri_at_iahu.com> wrote in message
> news:<DxBsb.30$1n1.179_at_news.oracle.com>...
> > > > Ordered domains do have logical order. Relations have no order, but
> the
> > > > values in the relations have order.
> > >
> > > That totally depends whom you ask, of course. A person with
mathematical
> > > background would have no trouble defining an order relation among the
> tuples
> > > of the original relation induced by the order defined on each domain
> > > associated with individual column.
> >
> > I think the answer is due to the intended "real-life" meaning of
> > relations.
> > Clearly in general a set can have an ordering defined on it.
> > But a relation isn't just any old set, it is a set of *logical
> > propositions*.
> > So:
> >
> > 1) the grass is green.
> > 2) the sky is blue.
> >
> > means exactly the same as:
> >
> > 1) the sky is blue.
> > 2) the grass is green.
> >
> > i.e. P1 AND P2 = P2 AND P1
> >
> > where P1, P2 are the propositions above.
> > So you could say the fact that relations can't have an order comes
> > down to the commutativity of the logical AND operator.
>
> What about numbers that you have in front of your propositions? When I ask
a
> list of propositions returned as a result of my query, I would like to
have
> an extra column that has integers numbers in it. Those numbers have to be
> calculated from the values in the "symantically valid columns". SQL with
> analytical extensions (window functions) generates such enumerating column
> easily. How about other languages: RA, RC, Datalog, and D4?

If you had quota queries, what need would you have for these numbers? Received on Fri Nov 14 2003 - 03:10:49 CET