Natural key
A natural key is an identifier formed from meaningful domain attributes whose values uniquely identify an entity or record.
100 SQL Server Mistakes and How to Avoid Them
A natural key is a key formed from attributes that have inherent business meaning and identify an entity.
- How it is used
- Uses natural keys to identify entities and connect normalized relations through primary and foreign keys.
- How deep it goes
- Defines natural, artificial, and composite keys, then relates composite keys to functional dependency in 2NF.
- Examples
- Uses SocialSecurityNumber and EmployeeID, then models email, company, area, and product attributes in sales relations.
- What you can do after
- Evaluate/understand whether a business attribute can identify an entity or whether an artificial key is needed.
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Java Persistence with Spring Data and Hibernate epub
A natural key is a primary key derived from meaningful attributes of the represented entity or domain data.
- How it is used
- Guides primary-key selection by testing whether business attributes provide stable identity for persistent entities.
- How deep it goes
- Explains business meaning, stability requirements, candidate keys, and foreign-key consequences, but does not develop composite-key implementation details.
- Examples
- Uses Social Security Number, Australian Tax File Number, item numbers, and USERNAME as business-meaningful key examples.
- What you can do after
- Evaluate/understand when a natural key threatens schema stability and when a surrogate key better separates database identity from business data.
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Functional Design and Architecture: Examples in Haskell
A natural key is a database key formed from one or more attributes that have inherent meaning in the represented domain.
- How it is used
- Guides relational key design by exposing when meaningful domain fields should yield to a surrogate identifier.
- How deep it goes
- Explains composite natural-key drawbacks and contrasts surrogate keys, stopping short of a general key-selection procedure.
- Examples
- Uses meteor records, a FLOAT/FLOAT/TIMESTAMP composite key, floating-point comparisons, and integer or UUID identifiers.
- What you can do after
- Evaluate database key designs by testing precision, query cost, relationship overhead, and expected field changes.
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Related concepts
- business keyequivalent to · A business key is one or more domain-meaningful properties whose values identify a business entity or distinguish it for matching and uniqueness.
- keykind of · A key is an identifier or value used to locate or access an associated entry or property in a keyed data structure.
- artificial keycontrasts with · An artificial key is a key with an assigned value that has no inherent business meaning, such as an incrementing identifier.
- surrogate keyalternative to · A surrogate key is an artificially assigned, domain-independent identifier used to uniquely identify a database record independently of its business attributes.
- candidate keykind of · A candidate key is a minimal set of attributes whose values uniquely identify each row in a relational relation.
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