Re: Demo: Modelling Cost of Travel Paths Between Towns

> So if state boundaries are changed and the city of Unreal, PA will
> henceforth be part of Texas, changing the row for Unreal, PA to Unreal, TX
> would corrupt the db?

Reading thru the earlier posts, it seems I have lost context of the thread.

> 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

What I failed to catch here was:
1) Alan was not able to rename town c to a in the original RM solution presented by Celko.
2) The original RM solution requires changes to schema to accomodate two towns with the same name.

The above problems resulted because Celko's original one-table schema represented cities redundantly. It should have had a separate table for cities. In XDb2's solutions, the towns are already normalized. Received on Mon Nov 15 2004 - 21:19:40 CET