Re: Objects and Relations

On 24 feb, 13:43, "Cimode" <cim..._at_hotmail.com> wrote:

> If you define class by domain then what is the RM equivalent for
> relation?

You probably mean the OO equivalent for relation.

OO lacks an equivalent for relation. That's why it is so difficult to write database applications using OO languages.

> In RM, a domain is *not* the same* as a type or a relation.

In RM domain is used as a synonym of type and it is completely different to relation.

> (
> domain = set of *possible* values for which a relation draws
> *possibly* values

When you say "relation" we assume that you mean "relation value". If you mean "relation variable" please write: "relation variable" or "relvar".

On the other hand, a domain is a set of any kind of values: scalar, relational, tuple, array, etc.

> typing = making a domain from a relation body and name (therefore
> only *existing* values for a specific relation).

I don't see any sense here.

Regards Received on Mon Feb 26 2007 - 11:20:18 CET