<P> A surrogate key (or synthetic key, entity identifier, system - generated key, database sequence number, factless key, technical key, or arbitrary unique identifier) in a database is a unique identifier for either an entity in the modeled world or an object in the database . The surrogate key is not derived from application data, unlike a natural (or business) key which is derived from application data . </P> <P> There are at least two definitions of a surrogate: </P> <Dl> <Dt> Surrogate (1)--Hall, Owlett and Todd (1976) </Dt> <Dd> A surrogate represents an entity in the outside world . The surrogate is internally generated by the system but is nevertheless visible to the user or application . </Dd> <Dt> Surrogate (2)--Wieringa and De Jonge (1991) </Dt> <Dd> A surrogate represents an object in the database itself . The surrogate is internally generated by the system and is invisible to the user or application . </Dd> </Dl> <Dt> Surrogate (1)--Hall, Owlett and Todd (1976) </Dt>

What my sql property is used to create a surrogate key in my sql