CDM: Primary identifier?

[kawu]

Hi all!

I have started out with Sybase PowerDesigner 9.5, but I can't figure out, what a "primary identifier" is used for. Whenever I flag an attribute to be primary, that seems to do the job for me, but why is there the need for an identifier. Is it simply to give the identifying attributes one descriptive name? What is it for?

Thanks for helping!

Karsten

 

[markrem]

Primary identifiers in the conceptual data model (CDM) become primary key constraints in physcial data models (pdm). For example, if you transform your CDM into a PDM targeted at Oracle, then your primary identifier will generate a primary key constraint which implements the necessary not null and unique constraints behind the scenes.
-Mark