Natural, Artificial, Exposed and Surrogate Keys Explained

IntelligentEnterprise : Celko on SQL: Natural, Artificial, Exposed and Surrogate Keys Explained (printable version)

By Joe Celko

There is no such thing as a “universal, one-size-fits-all” key. Just as no two sets of entities are the same, the attributes that make them unique have to be found in the reality of the data. You can decide on the kind of key you want to use based on the nature of your particular situation.