Simple conditions for guaranteeing higher normal forms in relational databases

ABSTRACT

A key is simple if it consists of a single attribute. It is shown that if a relation schema is in third normal form and every key is simple, then it is in projection-join normal form (sometimes called fifth normal form), the ultimate normal form with respect to projections and joins. Furthermore, it is shown that if a relation schema is in Boyce-Codd normal form and some key is simple, then it is in fourth normal form (but not necessarily projection-join normal form). These results give the database designer simple sufficient conditions, defined in terms of functional dependencies alone, that guarantee that the schema being designed is automatically in higher normal forms.

REFERENCES

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INDEX TERMS

Primary Classification:
  H. Information Systems
  H.2 DATABASE MANAGEMENT
      H.2.1 Logical Design
          Subjects: Normal forms

General Terms:
Design, Theory

Keywords:
5NF, BCNF, Boyce-Codd normal form, PJ/NF, database design, fifth normal form, fourth normal form 4NF, functional dependency, join dependency, multivalued dependency, normalization, projection-join normal form, relational database, simple key