【摘 要】
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It is very important to use database technology for a large-scale system such as ERP and MIS. A good database design may improve the performance of the system.
【机 构】
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Department of Computer and Engineering,Department of Computer and Technology,School of Computer and
论文部分内容阅读
It is very important to use database technology for a large-scale system such as ERP and MIS. A good database design may improve the performance of the system. Some researches show that a γ-acyclic database scheme has many good properties, e.g., each connected join expression is monotonous, which helps to improve query performance of the database system. Thus what conditions are needed to generate a γ-acyclic database scheme for a given relational scheme? In this paper, the sufficient and necessary condition of the existence of γ-acyclic, join-lossless and dependencies-preserved database schemes meeting 4NF is given.
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