Surrogate key
A surrogate key is an artificially assigned, domain-independent identifier used to uniquely identify a database record independently of its business attributes.
Grokking Relational Database Design
A surrogate key is an artificially created key value used to uniquely identify a row independently of the row's natural attributes.
- How it is used
- Identifies rows when no stable natural attribute can serve as a primary key.
- How deep it goes
- Explains auto-incrementing numeric IDs and their duplication limitation, then applies unique constraints to customer and dealer design.
- Examples
- Uses review_id for reviews and customer_id for customers whose email addresses and phone numbers can change.
- What you can do after
- Apply it by choosing an auto-incrementing ID for row identity and adding unique constraints where duplicate natural data is unacceptable.
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Java Persistence with Spring Data and Hibernate epub
A surrogate key is an application-meaningless primary key whose purpose is to identify stored data internally.
- How it is used
- Uses internal identifiers to decouple database identity from mutable or absent business keys.
- How deep it goes
- Explains rationale, foreign-key consequences, schema tradeoffs, and generation configuration, but defers Java-domain representation and generation strategies.
- Examples
- Uses USERS and BILLINGDETAILS tables with generated ID columns and a USER_ID foreign key.
- What you can do after
- Evaluate primary-key choices and configure generated identifiers when designing persistent tables and ORM mappings.
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DuckDB in Action
A surrogate primary key is an artificially assigned identifier used as the primary key of a table instead of being derived from business data.
- How it is used
- Uses artificial identifiers to address rows when business attributes are not reliably unique.
- How deep it goes
- Defines surrogate keys and demonstrates sequence-backed creation, while contrasting them with externally generated and composite keys.
- Examples
- Demonstrates an externally generated system ID and a sequence-backed price ID in an energy-consumption schema.
- What you can do after
- Build it from scratch with SQL sequences, primary-key declarations, and separate business-uniqueness constraints.
Related concepts
- composite keyalternative to · A composite key is a key formed from multiple attributes or values whose combination identifies or uniquely distinguishes a record or item.
- primary keyimplements · A primary key is a designated column or attribute, or combination of them, that uniquely identifies each row or item in a table or data store.
- natural keyalternative to · A natural key is an identifier formed from meaningful domain attributes whose values uniquely identify an entity or record.
- business keyalternative to · A business key is one or more domain-meaningful properties whose values identify a business entity or distinguish it for matching and uniqueness.
- @GeneratedValueconfigured by · @GeneratedValue is a Jakarta Persistence annotation that configures automatic generation of an entity identifier according to a specified strategy.
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