用扩展的实体—联系方法描述学科体系结构的概念模型。
The conceptual model of the discipline architecture is represented through an extended entity-relationship approach.
在设计层次型数据库时，一个较好的设计方法是分二步走：首先利用实体联系方法抽象出现实世界的实体联系模型，然后将实体联系模型变换到具体DBMS 所支持的层次型模型。
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.
在设计层次型数据库时，一个较好的设计方法是分二步走：首先利用实体联系方法抽象出现实世界的实体联系模型，然后将实体联系模型变换到具体DBMS 所支持的层次型模型。
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.
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