CompuServe Messages

The thing to note about the definition of primary keys (which I assume is what you want the SSN to be) is that they must be unique *and* they must not be NULL. Usually, if you want to violate this rule, then you haven't well defined your entities in your database. Also, from what I've seen of Superbase's relational modeling capabilities, you can create most models, but you have to be very scrupulous in your model (because of the lack of true NULL support). In your problem, it sounds like what you have is a list of all people (call it TableA) and a list of people with SSNs (call it TableB). The primary key of TableA would be generated by SER() (with a unique index) and would have a new entry added whenever a new person is added to the database. The primary key of TableB would be the primary key value from TableA whenever the person is given an SSN. You would then probably generate a form that combines the two tables appropriately and you might want to have a LOOKUP function on TableB's PK to ensure that it exists in TableA.