Re: Object-oriented thinking in SQL context?

"none (Reinier Post)" <rp_at_raampje.> wrote in message news:4a2edac9$0$27727$703f8584_at_news.kpn.nl...

> The entity-relationship method is often used, advocated and taught
> for the design of databases. The design starts by creating
> an entity-relationship diagram, that is systematically transformed
> and provided with implementation detail until an ER diagram results
> that specifies a relational database schema.

Back when I learned databases, ER modeling (including diagrams) was NOT used for design purposes. It was used for data analysis. analysis and design are easily confused with each other, but they are not the same thing. The same would go for OOA and OOD. The fact that database design features don't go into an ER model is not a limitation of ER. It's a feature.

That means that you can start with ER and from there move forward to designing relations or SQL tables, or CODASYL sets, or IMS hierarachies or presumably some kind of persistent objects in an OODBMS, if there were such a thing.

>
> An ER diagram is a representation of the relations (tables)

Entities are not tables, or relations. It only looks that way. Received on Wed Jun 10 2009 - 00:52:40 CEST