空值环境下关系模式到(N)3NF的保FD、无损连接分解

Decompositions for Relational Schema Under Null Value Circumstances Into 3NF With preservation of NFD's and Lossless Joins

摘要: 本文讨论了空值环境下有关不完全关系模式到(N)3NF 的保NFD 及无损连接分解问题,给出了不完全关系模式分解成空值环境下3NF 的充分且必要条件,针对不完全关系模式的特殊性质给出分解为(N)3NF 保NFD 且具有无损连接性的分解算法.

Abstract: The problem of decompositions to (N)3NF is discussed in this paper.The full and essential conditions of the compositions are given.In point of the special property of incomplete relational schema,the decomposition algorithm with preservation of NFD's and lossless joins is given.