What is a derived (artificial) primary key

Question

What is a derived (artificial) primary key? When must this be used?

Answer 1

Using a name like the primary key violates the principle of stability. The social security number may be a valid choice, other than a foreign employee may not have a social security number. It is a case where a derived, quite than a natural, primary key is suitable. A derived key is an artificial key which you create. A natural key is one which is already part of the database.