Re: Evolution of Date's "Abstract Machine" (via CM)

> Date goes on (in the above ref) to define two meanings for the
> term "data model". The first and more fundamental meaning is given
> in the above definition.

Yes, we have this term model but we unfortunately don't have a uniform terminology for distinguishing at what level we are speaking. In other areas it is common to have separate terms to clarify this; even though one might use the same term, it's too confusing. Thus, one often finds a set of sets referred to as a "class" even though it is also a set.

I have begun using the term "metamodel" to describe the models that SQL, C++, Java, etc. provide to users of those languages. (It's not a great term, but it's the best I've come up with.) Thus we can speak of comparing the C++ metamodel to the Java metamodel, or we can speak of comparing the SQL metamodel to the TTM one.

Marshall Received on Sat Jun 04 2005 - 10:06:11 CDT