Re: I am confused as to whether I should use numeric IDs or not

Joseph Godfrey wrote in message <389A54CD.415CF4B5_at_ecologic.net>...
>I think the point about an OID not being an explicit attribute is one way
 to
>approach the question. But in object-relational databases OIDs are
explicit.

Are they explicit _attributes_ that work just the way other attributes work, with all the same syntax and capabilities? I'm not familiar with any actual ORDBMSs so I honestly don't know the answer to this question. Date seems to say that OIDs are "special", different in some way, and that's why he objects to them.

>Furthermore, autonumbering (as in MS Access, Informix, Oracle, etc) is not
 the
>same thing as an id that has semantics, e.g., a social security number,
 order
>id, customer number, etc.

I'm not sure I understand the distinction. What semantics does my SS# have? As far as I know it's just a unique id that the government uses to keep track of my identity. I don't know what algorithm was used to generate it, but I'd assume it's something resembling an autonumbering technique. What's the difference between a unique id generated by autonumbering, and a unique id like SS#?

>Very often the ID is hidden from view, as in the
>question that initiated this thread. An autonumber in this case is not an
>attribute of the data but a bookkeeping deviceof the database system very
 much
>akin, I think, to an OID.

I guess the question here is, whose view is it hidden from? Anybody manipulating the data at the SQL level certainly needs to "see" the id attribute, whether they're writing an application or just typing in queries interactively. What about users who enter and browse data using forms: should they see the id attribute or not? Well, I think they should be able to see it if they want to, but that's probably a question best left to the UI designers. The most important thing is that the _programmers_ be able to use the id just like every other attribute.

>Furthermore this way of using ids can circumvent
>referential integrity constraints. If one includes the abstract ID as part
 of
>the primary key and keeps the entire key explicit, I understand that this
>conforms with relational theory and referential integrity can be enforced..
 But
>autonumbering is often not used this way -- and that I think is trouble.

Agreed. The id absolutely needs to be declared as a key. Usually it should be the primary key, I would think (though relational theory doesn't have much to say on the issue of _primary_ keys per se). The post that originated this thread did assume that the id is the primary key, so in this case I don't think the trouble you're concerned about will occur. Received on Fri Feb 04 2000 - 00:00:00 CET