Definition - What does Surrogate Key mean?
Techopedia explains Surrogate Key
A surrogate key is not always used as a primary key, and this depends on whether the database is of the current or temporal kind. A current database only stores valid current data and requires a one-to-one association between the surrogate key in the modeled world and the primary key of the database, in which case the surrogate may act as the primary key. However, in a temporal database, there is a many-to-one association between the primary keys and the surrogate key, which means that there may be multiple objects within the database that are associated with the surrogate key, so it cannot be used as a primary key.
A surrogate key has the following characteristics:
- The value is never reused and is unique within the whole system.
- It is system generated.
- The value cannot be manipulated by the user or application.
- The value is not an amalgam of different values from multiple domains.
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