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what is the difference between cardinality rules and data integrity rules?
A. Referential integrity rules quantify the relationships between two or more entities and cardinality rules quantfy the common attributes across entities.
B. Referential integrity rules define the quantity of each entity instance that can participate in a relationship between twoentities and cardinality rules ensure valid values
C. There is no difference.Cardinality rules and referential integrity rules are synonyms.
D. Cardinality rules define the quantity of each entity instance that can participate in a relationship between two entities and referential integrity rules ensure valid values
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正确答案是:D: Cardinality rules define the quantity of each entity instance that can participate in a relationship between two entities and referential integrity rules ensure valid values。

专业分析:

1. **Cardinality Rules(基数规则)**:
- 基数规则定义了在两个实体之间的关系中,每个实体实例可以参与的数量。例如,在一个“一对多”的关系中,一个实体实例可以与多个另一个实体实例相关联,而在“多对多”的关系中,多个实体实例可以相互关联。
- 基数规则通常用于定义数据库中的关系类型,比如一对一、一对多和多对多等。

2. **Referential Integrity Rules(参照完整性规则)**:
- 参照完整性规则确保在数据库中的关系是有效的,通常通过外键约束来实现。这意味着一个实体的外键必须对应另一个实体的主键,确保数据的一致性和完整性。
- 例如,如果一个订单记录引用了一个客户记录,参照完整性规则确保引用的客户记录必须存在。

综上所述,基数规则侧重于定义实体之间的关系数量,而参照完整性规则则侧重于确保这些关系中的数据是有效的和一致的。