Re: Pizza Example

> But if you have an ER model you don't have a database design.

That's the whole point. The ER model is useful for what it doesn't say, as much as for what it does say. It does establish the connection between the data, expressed in values and domains, and the subject matter, expressed in entities, relationships, and attributes.

It requires a little work to turn this into either a relational model or a CODASYL model, but you haven't hidden the design decisions in the ER model, where they are hard to see.

By spearating out data design from database design, it makes things clearer, as far as I'm concerned.

>You can not turn a relational database design in a ER model in almost all
cases.

I didn't get this point. What are you saying? Received on Sat Apr 24 2004 - 15:45:20 CEST