constraints in algebra instead of calculus

Okay, a while back we were talking about writing constraints in a language with aspects of the relational calculus, specifically the existential and universal quantifiers. The point was made that that's unnecessary; the calculus is no more expressive than the algebra.

So it ought to be possible to write any constraint from the calculus in the algebra.

Well, I'm having a hard time figuring out how to do it. Can anyone help?

How does one write a functional dependency in the algebra? A foreign key?

Marshall Received on Sun May 20 2007 - 01:00:04 CDT