Re: relational db design question

Evan Keel wrote:
> ... You are correct in making Magazine, Book, etc subtypes
> of Reference, at least at the logical level.

You don't know what the OP wants to accomplish with his database. Is it relevant to the users of the database to distinguish between types of references? It depends on that.
Can we tell every type of reference in advance? SMS, email, usenetposting - how to reference that? NNTP or google?

> You can implement this in three
> ways:
>
> - one big table allowing nulls
> - many subtype tables
> - a supertype/subtype tables with discriminator
>
> Google "implementing subtypes".

Or, without complete subtyping, two columns: protocol, locator Received on Thu Feb 08 2007 - 17:46:37 CST