Natural key

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In relational model database design, a natural key is a key that is formed of attributes that already exist in the real world. 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.

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.

External links[edit]

  • "Intelligent Versus Surrogate Keys", B Carter .
  • "Avoid Unique Indexes – (Mistake 3 of 10)", Near Infinity, Create Data Disaster .
  • "Natural versus surrogate keys", c2 .