問題詳情
40、Which of the following descriptions about foreign key are not correct?
(A) Foreign key must refer to the primary key of other relation.
(B) Foreign key is not necessary a primary key in its own relation.
(C) Foreign key must have the same name as the primary key it refers to.
(D) Foreign key cannot have null value.
參考答案
答案：C,D
難度：非常困難0
統計：A(0),B(0),C(0),D(0),E(0)