实体及关系处于第一等级，用复合数据模型元素表示。
Entities and relationships are first class citizens and are represented by the CompositeData model element.
在概念模式后出现的是逻辑模式——用更多的细节定义概念，并显示实体之间的关系的数据模型。
After the conceptual schema comes the logical schema — the data model that defines the concepts with greater detail and shows the relationships between the entities.
在概念模式后出现的是逻辑模式——用更多的细节定义概念，并显示实体之间的关系的数据模型。
After the conceptual schema comes the logical schema — the data model that defines the concepts with greater detail and shows the relationships between the entities.
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