【摘要】 关系数据库理论中给出的完全连接依赖的有效公理系统并不能完全适应应用的需要 ,本文在对有效公理系统的研究基础上对其作出扩充 ,使其应用范围更为广泛 ,并能直接用于找出蕴含的所有连接依赖及判断连接依赖是否存在推导有向无回路图DAG。更多还原

【Abstract】 Valid axiom system based on completeness join dependency which is given from the theory of relation database can’t completely adapt to the need of application. In the text some extensions are made for valid axiom system on the basis of the research of valid axiom system so as to apply widely. Moreover, the conlusion can be directly used for searching all the implicative join dependency and judging whether the join dependency can infer DAG or not.更多还原