O Joost Kraaijeveld έγραψε στις Nov 22, 2005 :
> Hi,
>
> Is there a way to create a foreign key to 2 tables: e.g. a bankaccount
> table that has a column "owner", that must point to a record in either
> the customer or the supplier table?
While there are techniques to accomplish this,
i see a problem:
How do you know if a certain value in owner is to be joined
with e.g. customer and not supplier??
The right way is to have 2 columns that can be null,
pointing to customer,supplier respectively,
and then write a trigger to ensure that exactly one
is not null.
>
>
> TIA
>
>
--
-Achilleus
