Re: Generating the foreign key constraints

Dan,

> I am using PowerDesigner 8.0 (PowerAMC 8.0) to create conceptual
> models for my database. I have a small problem: should I include the
> foreign key in an entity or use the one generated in the physical model
> by PowerDesigner ?

I recommend using the one generated in the physical model by PD, and not including your own foreign keys in the CDM.

In a conceptual model, FKs are superfluous. FKs implement relationships. At the conceptual level, relationships are identified and diagrammed, but not implemented. This is in keeping with the notion that the CDM reflects analysis, while the PDM reflects design.

If you need further convincing, try this: Try it both ways. Then take a close look at the CREATE TABLE commands generated by PD. I believe you will find that, if you put your own foreign keys into the conceptual model, you will find a redundant set of foreign keys generated by PD, in the final CREATE TABLE commands. I can't check this out here, because I don't have PD available to me, but that's how I recall it working. Received on Thu Aug 01 2002 - 20:41:28 CEST