>You can express a foreign key constraint that these tables must link to an employee, but not the other way around. You can’t guarantee in the limited type system of SQL that every employee row has a corresponding employee_X table, and exactly one, not more.
in this case instead of an employee table you would have an employee view that’s the union of the separate tables - engines vary dramatically in what sort of constraints they’ll enforce on the view now but the relational model is fine
in this case instead of an employee table you would have an employee view that’s the union of the separate tables - engines vary dramatically in what sort of constraints they’ll enforce on the view now but the relational model is fine