Another raw same as primary key

Curious as to why you want to do this? A 3rd Normal Form database tries to remove duplicate data and what you're asking for moves away from that. What is it that this will give you that having the value only  as the primary key does not?

Curious as to why you want to do this? A 3rd Normal Form database tries to remove duplicate data and what you're asking for moves away from that. What is it that this will give you that having the value only  as the primary key does not?