Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?
Date: Tue, 25 Feb 2003 02:32:36 -0500
"Paul Vernon" <paul.vernon_at_ukk.ibmm.comm> wrote in message
> "Bob Badour" <bbadour_at_golden.net> wrote in message
> > > Let me put it this way. If a type has 2 possiable representations,
> > > A) the number of values represented by PosRep1 must equal the
> > > of values represented by PosRep2
> > > B) each value represented by PosRep1 must 'map' to exactly one
> > > represented bt PosRep2, and versa.
> > While desirable whenever possible and while certainly possible in an
> > machine, I do not require this of physical implementations.
> Yes and that is my worry. I'm not comfortable with such a fudge. If the
> logical model cannot be implemented correctly then is there not something
> wrong with the model?
First, I would disagree that the implementation is incorrect. Second, I would observe that a logical data model is an ideal abstraction. Third, I would observe that any flaw lies in the physical implementation and not the logical data model. Fourth and finally, I must ask: What other logical data model do you propose that addresses the specific issue of cartesian and polar coordinates and possible rounding in the internal physical representation?
After you demonstrate we live in an infinite and continuous universe, I'll get back to you.
> this not the whole point of Date's work:
> Theory IS Practical
In what way is it not practical?
> With my addition: (otherwise the theory is broke)
> Paul Vernon
> Business Intelligence, IBM Global Services
Received on Tue Feb 25 2003 - 08:32:36 CET