Summary

Database normalization is a process performed on your tables to make them less likely to fall prey to various common kinds of data anomaly:

  • 1st normal form contains no repeating groups and guarantees that all attributes are dependent on a primary key.

  • 2nd normal form contains no partial dependencies.

  • 3rd normal form contains no transitive dependencies.

  • For practical purposes, 3rd normal form is usually sufficient; indeed, overnormalizing can lead to performance issues, with the database having to perform too many joins.

  • Boyce-Codd normal form ensures each determinant is a candidate key.

  • 4th normal form contains no more than one multivalued dependency.

  • 5th normal form ensures tables cannot be reduced to smaller tables with different keys.

  • Domain key normal form is a theoretical ideal beyond the scope of this book.



Mastering MySQL 4
Mastering MySQL 4
ISBN: 0782141625
EAN: 2147483647
Year: 2003
Pages: 230
Authors: Ian Gilfillan

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