2. 在将E-R图转换为关系模型时，一般都将m:n联系转换成一个独立的关系模式。下列关于这种联系产生的关系模式的主键的说法，正确的是（）。 - 查题网

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国家开放大学 / 数据库应用技术

2. 在将E-R图转换为关系模型时，一般都将m:n联系转换成一个独立的关系模式。下列关于这种联系产生的关系模式的主键的说法，正确的是（）。

A.
只需包含m端关系模式的主键即可

B.
只需包含n端关系模式的主键即可

C.
至少包含m端和n端关系模式的主键

D.
必须添加新的属性作为主键

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