Re: Plural or singular table names

"Paul Vernon" <paul.vernon_at_ukk.ibmm.comm> wrote in message news:<bj59dh$13i2$1_at_gazette.almaden.ibm.com>...

> > > Relation variable or relation value?

In D&D books relation means value and relvar variable.

> Nope, a type is part of the value.

According to Date, values always carry with their type or types, but I don't think that a type is part of the value.

I always carry with my wallet when I go out, but my wallet is not a part of me :-)

> A relation value has no information about constraints. It might satisfy certain
> constraints, but it does not 'contain' any constraints. It might satisfy A ->

Agreed, and in TTM keys are not part of the relational types (at least in the examples), they are shorthands for database constraints which are part of the database type.

Tutorial D's relation type generator doesn't allow to declare candidate key constraints.

I find the idea of values having constrains as an absurd. Values are constants. We can not constraint a constant.

Regards
  Alfredo Received on Mon Sep 08 2003 - 01:31:15 CEST