关键词: 规范化, 模式分解, 保持函数依赖

Abstract:

Normalization can improve the normal form degree of relations through schema decompositions,and the criteria are lossless join and preservation of functional dependencies.A theorem on preservation of functional dependencies is proved,and it is shown that the significance of preservation of functional dependencies do not affect the performance of data updates while reducing data redundancy.The concrete analysis of an example further confirms the conclusion.

Key words: normalization;schema decomposition;preservation of functional dependencies