Encyclopedia of Database Systems

2009 Edition
| Editors: LING LIU, M. TAMER ÖZSU

Boyce-Codd Normal Form

  • Marcelo Arenas
Reference work entry
DOI: https://doi.org/10.1007/978-0-387-39940-9_1245

Synonyms

 BCNF

Definition

Let R(A1,...,An) be a relation schema and Σ a set of functional dependencies over R(A1,...,An). Then (R, Σ) is said to be in Boyce-Codd Normal Form (BCNF) if for every nontrivial functional dependency XA implied by Σ, it holds that X is a superkey for R.

Key Points

In order to avoid update anomalies in database schemas containing functional dependencies, BCNF was introduced by Codd (In [2], Codd pointed out that this normal form was developed by Raymond F. Boyce and himself.) in [2]. This normal form is defined in terms of the notion of superkey as shown above. For example, given a relation schema R(A, B, C) and a set of functional dependencies Σ = {ABC, CB}, it does not hold that (R(A, B, C), Σ) is in BCNF since C is not a superkey for R. On the other hand, (S (A, B, C), Γ) is in BCNF if Γ = {ABC}, since A is a superkey for S in this case.

It should be noticed that relation schema R(A, B, C) above is in 3NF if Σ = {ABC, CB}, although this...

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Recommended Reading

  1. 1.
    Beeri C. and Bernstein P. Computational Problems Related to the Design of Normal Form Relational Schemas. ACM Trans. Database Sys., 4(1):30–59, 1979.CrossRefGoogle Scholar
  2. 2.
    Codd E.F. Recent Investigations in Relational Data Base Systems. In Proc. IFIP Congress. 1974, pp. 1017–1021.Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Marcelo Arenas
    • 1
  1. 1.Pontifical Catholic University of ChileSantiagoChile