The entity-relationship(E-R) data model is based on a perception of a real world that consists of a collection of basic objects, called entities, and of relationships among these objects.
实质-联系 （电子半径）数据模型以有一个基本物件的集合物件，叫做了实质的真正世界的一个知觉为基础，和在这些物件之中的联系。
The entity-relationship(E-R) data model is based on a perception of a real world that consists of a collection of basic objects, called entities, and of relationships among these objects.
实质-联系 （电子半径）数据模型以有一个基本物件的集合物件，叫做了实质的真正世界的一个知觉为基础，和在这些物件之中的联系。
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