A surrogate key 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.
There are at least two
definitions of a surrogate:
Surrogate (1) – Hall,
Owlett and Todd (1976)
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. [1]
Surrogate (2) –
Wieringa and De Jonge (1991)
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.
No comments:
Post a Comment