Re: Multiple Parent Tables (or Multiple Inheritence, or Arc-Relationships...)

> Hi, Dave:
>
> Page 40 of Silverston, et al.'s book _The Data Model Resource Book_?
> describes a supertype of PARTY with two subtypes, PERSON and
> ORGANIZATION. This supertype is then linked to an ADDRESS entity via
> an intersection entity called PARTY_ADDRESS (naturally ;-). Thus you
> have addresses for people as well as businesses.
>
> In my experience, it's uncommon to see the PARTY supertype implemented
> as-is. Usually PERSONs and ORGANIZATIONs are implemented as stand-
> alone tables, each with their own intersection entity to the single
> ADDRESS table, as you describe above.
>
> --Jeff

Thanks. I think that's what I really wanted to know: "How is it actually normally done?" I could see a number of solutions driven from the theory, but found most of them felt contrived or over engineered. I am never going to need to refer to PARTYs, so constructing it just to let two different and independant entities have addresses seemed...wrong.

If I was designing a vehicle database, and was tracking cars, trucks, and motorcycles I could see a VEHICLE supertype, with specialized subtypes... but for handing the fact that a number of entities in the system could have an address?

Your confirmation/observation that while conceptually it fits into the gen-spec or supertype/subtype problem but in practice its not normally implemented that way was very helpful.

Thanks again.
-Dave Received on Thu Dec 13 2007 - 17:14:06 CST