Re: candidate keys in abstract parent relations

"Forrest L Norvell" <spankysyourpal_at_gmail.com> wrote in message news:1137556243.101621.119250_at_o13g2000cwo.googlegroups.com...

> 4. The hard part: An Album is a collection of Tracks by a Credited
> Performer with a Title. The difficulty comes in because I'm trying to
> be scrupulous, and defining uniqueness on those attributes is proving
> to be very difficult.

This surprises me, although maybe it's just my ignorance of the subject matter.

If some Label released an Album entitled "Billboard Hits of the Sixties", I would expect it to be an anthology of tracks drawn from the works of different performers.

I'd also expect the title to be ambiguous, having been used by more than one Label, for an entirely distinct set of tracks.

Identity is much more subtle than it appears at first. If students are distinguished by a unique "student number" that gets assigned by admissions in such a way that no two students ever get the same number, the consequences are identical to what would have been the case if the software had assigned the students a surrogate key called "Student Number". The only difference is that we conceive "admissions" as part of the "user community", and we like to avoid exposing surrogate keys to users. But that's not an ultimately philosophical difference. Received on Fri Jan 20 2006 - 06:33:12 CET