Re: XQuery question

Based on your reply I think I misunderstood your original question. In the relational model we also would say that a car has a relationship with color. But this is informal.

The way this relationship is formally captured in a relational model varies. In the most general case, a Many to Many relationship, this would be captured using a third table, sometimes called a join table or an intersection table. It has k1+k2 columns, where k1 is the number of columns in the primary key of the car table and k2 is the number of columns in the primary key of the color table.

neo55592_at_hotmail.com (Neo) writes:

> > > Here there are no relations between relation T_Car and T_Color. Some
> > > might say T_Car has a "relation" to T_Color but this would not make
> > > sense in rdm-speak since a relation is defined as "a set of tuples".
> > > What formal word has rdm defined to described this type of "relation"
> > > between T_Car and T_Color?
> >
> > The formal term is "Cartesian product". This is taken directly
> > from set theory. This concept is sometimes also called a "cross
> > product" (which is a slight misnomer), or a "product join".
>
> In symbolic logic, one might say a car has a relation to color,
> and in ER model, one might say a car has a relationship to color.
> In rdm, a car has a cartesian product with color, would be equivalent?

-- 
Hopefully helpfully yours,
Steve
-- 
Steven Tolkin    steve . tolkin at fmr dot com   617-563-0516 
Fidelity Investments   82 Devonshire St. V4D     Boston MA 02109
There is nothing so practical as a good theory.  Comments are by me, 
not Fidelity Investments, its subsidiaries or affiliates.