空值环境下广义连接依赖（NGJD）及推导规则的研究

Research of Generalized Join Dependency （NGJD） and Its Inference Rules Under Nun Value Circumstances

摘要: 本文给出了空值环境下广义连接依赖强保持、弱保持的概念。讨论了它们的推导规则，证明了各推导规则在强保持、弱保持条件下的存在性，以及相应的完备性结论。

Abstract: This paper gives the concepts of strong or weak holding of generalized join dependency under null value circumstances, discusses their inference rules, proves the existence of every inference rule under the condition of strong and weak holding and gives the relevant conclusions.