摘要
对于具有函数依赖 (FDs)约束的传统关系数据库规范化理论来说 ,判定一个 FD是否被给定 FD集所逻辑蕴涵 (即成员籍问题 )是非常重要的 ,这有助于设计有效的模式分解算法 .而对于具有时态函数依赖 (TFDs)约束的时态模式来说 ,由于多时间粒度的使用使成员籍问题的解决变得更加复杂 .由此讨论了时态类型的一些特性 ,并提出了有限决定集的概念 .基于求得属性的有限决定集 ,对每一个元素的左部属性集是单一属性的
For normalization theory of traditional relational databases with FDs constraints, it is important to identify whether a FD is logically implicated by given FDs (i.e. membership problem), which may help to design an available algorithm of scheme decomposition. For temporal database schemata with temporal dependencies (TFDs) constraints, the usages of multiple time granularities make it more difficult to solve membership problem. Thus some properties for temporal types are discussed, and the conception of the finitely determined set is proposed. In view of finding the finitely determined set of attributes, an available membership algorithm and the relevant proof for its correction are given for TFDs in which the set of left side attributes of each TFD only contains a single attribute.
出处
《计算机研究与发展》
EI
CSCD
北大核心
2002年第3期342-347,共6页
Journal of Computer Research and Development
基金
黑龙江省自然科学基金资助 (F 0 0 -0 6)
