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Home -> Community -> Usenet -> comp.databases.theory -> Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?
"Paul Vernon" <paul.vernon_at_ukk.ibmm.comm> wrote in message
news:b3dr5r$sss$1_at_sp15at20.hursley.ibm.com...
> "Bob Badour" <bbadour_at_golden.net> wrote in message
> news:zst6a.297$9O1.43758648_at_mantis.golden.net...
> > > Let me put it this way. If a type has 2 possiable representations,
then
> > > A) the number of values represented by PosRep1 must equal the
number
> > > of values represented by PosRep2
> > > B) each value represented by PosRep1 must 'map' to exactly one
value
> > > represented bt PosRep2, and versa.
> >
> > While desirable whenever possible and while certainly possible in an
ideal
> > 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?
> Some aspect of the world that it is not capturing?
After you demonstrate we live in an infinite and continuous universe, I'll get back to you.
> Is
> 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)
>
> Regards
> Paul Vernon
> Business Intelligence, IBM Global Services
Received on Tue Feb 25 2003 - 01:32:36 CST