Re: Partial foreign keys, check constraints and

On Thu, 2005-11-17 at 13:36, Eric E wrote:
> Eric E wrote:
>
> >> maybe you can solve it adding a new col and allow both to contain
> >> null values.
> >>
> >> if these are not mutually exclusive you can avoid a check if they are
> >> check that if one has a non-null value other has null...
> >
> > I did think about that, but I disliked the idea of two fields of nulls
> > for every one full field.... maybe it's not as bad a way of doing it
> > as I thought.
>
> BTW, in most cases I have 5+ tables to do this, so that's 4+ fields of
> null in each row...

Could you use some kind of intermediate join table, so that it pointed
to orders and then products / customers / othermidlevel tables pointed
to it, and so did the problems table?