Natural key

Not to be confused with Natural minor.

A natural key (also known as business key[1]) is a a type of unique key in relational model database design that is formed of attributes that already exist in the real world and used in business-related columns.[2] They are For example, a US citizen's social security number could be used as a natural key. In other words, a natural key is a candidate key that has a logical relationship to the attributes within that row. A natural key is sometimes called domain key.[3]

The main advantage of a natural key over a surrogate key, which has no meaning outside the database environment, is that it already exists; there is no need to add a new, artificial column to the schema. Using a natural key (when one can be identified) also simplifies data quality: It ensures that there can only be one row for a key; this single version of the truth can be verified because the natural key is based on a real-world observation.

References

  1. ↑ On Kinds of Keys
  2. ↑ Intelligent Versus Surrogate Keys
  3. ↑ Auto Keys Versus Domain Keys
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