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在关系数据库中,要求基本关系中所有的主属性都不能有空值,其遵守的约束规则是

单选题
2021-09-02 00:18
A、数据依赖完整性规则
B、用户定义完整性规则
C、实体完整性规则
D、域完整性规则
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正确答案
B

试题解析

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