Saad,
> I have 2 tables "A" and "B" in mySQL. They both have an attribute 'id'
> which is unique between the 2 tables. I want the union of these 2
> attributes to be a foreign key in a 3rd table "C". How do I specify
> this constraing in sql (mySQL) in table C? And for complex reasons I
> cannot merge the 2 tables A and B.
IMHO, you cannot do this in MySQL. How about upgrading to PostgreSQL? Then
we can help you.
--
-Josh Berkus
Aglio Database Solutions
San Francisco