Re: Plural or singular table names

"Bob Badour" <bbadour_at_golden.net> wrote in message news:pLn5b.425$QH3.43942973_at_mantis.golden.net... [snip]
> After I posted my other response, I thought of a way to drive the point
> home. See below:
>
> > > F:
> > >
> > > X Y Z
> > > = = =
> > > 2 2 4
> > >
> > > Do the following constraints give F different meanings?
> > >
> > > Z = X + Y
> > > Z = X * Y
> > > Z = X ^ Y
> >
> > If F is a variable then yes, if it is a value then no.
>
> Consider two scenarios. In the first, F above is a variable. In the second,
> G below is a variable.
>
> G:
>
> X Y
> = =
> 2 2
>
> In the second scenario, F is a value derived from G using one of the
> constraint expressions above making the expression part of the predicate of
> F and constraining the values that can appear in F.
>
> Do you see how the different constraints give F different meanings?
>

Ah but if F is 'derived' then F is actually a relational expression.

Do relational expressions have constraints. Yes - ones derived from the variables referenced and infered from the operators in the expresion.

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Wed Sep 03 2003 - 19:44:00 CEST