# 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

Message-ID: <mnF6a.332$QR3.51347581_at_mantis.golden.net>

"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
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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
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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 - 08:32:36 CET