Re: Demo: Modelling Cost of Travel Paths Between Towns

"Neo" <neo55592_at_hotmail.com> wrote in message news:4b45d3ad.0411161859.73560cc3_at_posting.google.com...
> > Ed: Matching that model in a Relational data model is easy enough.
> > Neo: This problem didn't not have highly variable data and relationships
> > or require a higher degree of normalization. Try adding a different
> > property to each city or name two cities the same. RM solution will
> > require some changes to schema and code already written against.
> > XDb2 solution will be minimally affected.
> > Alan: No big deal.
> > Neo: Please show how the current RM solution can work if two towns
> > are named the same (ie change name of town c to a).
> > Alan: The table would be thus: town PK, state PK, main_postal_code PK
>
> Alan, I was assuming we were contesting if Celko's orginal solution
> could handle the renaming of town c to town a, which I asserted it
> could not handle because his solution was not normalized. I thought
> you had simply added the name of town, state and postal code in
> Celko's table. After retracing the thread it now appear to me that you
> actually added three tables T_Town, T_State, T_PostalCode and linked
> their primary keys to Celko's table. So my arguments were invalid and
> incoherent.
>
> > ...but that's not the point, which you are still not getting.
> > This has been explained to you ad nauseum, and I will not do so again.
>
> Could you tell me which point I am supposed to be getting as I have no
> idea at this point.

I did not work from Celko's schema. I had not seen it when I did mine, and, I think I may have submitted mine first. The point you are not getting is what normalization is all about. IIRC, an excellent explanation was given by Hugo very recently where he made refernce to the distinction between the meaning of the data that is stored vs. the representation of the storage of the data, which is where you maintain your confusion regarding normalization. If you could get past that one concept, I think we would all be happy. Received on Wed Nov 17 2004 - 16:56:55 CET