Re: Relation problem

 wrote:
> On 19 Jan 2001 17:06:00 GMT, hidders_at_REMOVE.THIS.win.tue.nl (Jan
> Hidders) wrote:
>
> >That doesn't make the problem go away because then you have a "split"
> >foreign key from Patries to Individuals and Organisations.
>
> Supertype. Supertype.

I am afraid that these magic words also don't make the problem go away. :-)

This supertype is a generalization of Individuals and Organizations. That means that every Party is either an Individual or an Organization. This constraint leads to a split foreign key. If you don't implement this constraint then you haven't solved the prolem that there may be addresses in the Address table that don't belong to any Individual or Organization. And that is what the original problem was.

-- 
  Jan Hidders