Logical Data Modeling - Natural Key


A natural key is a type of primary key that is not controlled by your system.

Examples are all state identifications such

  • the VIN number for your car
  • the VAT number of your company
  • the SSN (social security number) for a person

This type of key is rarely used in practice as primary key because:

  • they may change (they are not controlled by your system)
  • they may not be available (people are not required to reveal their SSN)

If a primary key is not natural, it's a surrogate key (the most used type of primary key)

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