This system used E-R chart method to design in order to minimum data redundancy and optimize data consistency and reduce updating abnormity.
本系统采用E - R图法进行规范化设计使得数据冗余最小，数据一致性好，更新异常问题不易发生。
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A good algorithm to design such a hierarchical database consists of two steps, first, to describe real world in E-R model and then, convert it to the model supported by the DBMS.