Re: Plural or singular table names

"Bob Badour" <bbadour_at_golden.net> wrote in message news:Lwn5b.422$0G3.43916381_at_mantis.golden.net... [snip]
> > > Consider the following relation:
> >
> > Relation variable or relation value?
>
> It doesn't matter. It is a relation with known constraints.

Whether something is a value or a variable doesn't matter?

> Values do have constraints; they have types.

Nope, a type is part of the value.

> The relation F with a binary
> key {X,Y} is different from a similar relation with a nullary key {}. A
> relation value has a predicate and a body.

Nope, a relation value has a heading and a body. The heading defines the type of the value and is part of that value.

You do not take a relation body and add some type constraints. A relation body cannot stand alone without it's header.

A relation value has no information about constraints. It might satisfy certain constraints, but it does not 'contain' any constraints. It might satisfy A -> B, but A -> B is not part of it's value - it would be redundant if it was because we could derive the fact that A -> B from the actual value of the relation.

A value is just a value. It is 'constrained' to be exactly the value that it is. OK, so maybe that is one constraint.

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Wed Sep 03 2003 - 19:43:33 CEST