E-R diagram

例句：

1. 1. In the E-R diagram, each entity is represented by a circle and its relationships are indicated by lines between the circles.
   在实体-关系图中，每个实体都用一个圆圈表示，它们之间的关系通过圆圈之间的线条来表示。
2. 2. The E-R diagram helps us to understand the relationships between different entities in a database.
   实体-关系图帮助我们理解数据库中不同实体之间的关系。
3. 3. The E-R diagram is used to model the relationships between entities in a database.
   实体-关系图用于建模数据库中实体之间的关系。