What are the prime attributes of relation R(A,B,C,D) with following dependencies:
关系R（A，B，C，D）具有以下依赖关系的主要属性是什么：
F={AB->C , C->D , D->A}
F = {AB-> C，C-> D，D-> A}
options are: i) A,B,C ii) A,B,D iii) A,B,C,D iv) B,C,D
选项包括：i）A，B，C ii）A，B，D iii）A，B，C，D iv）B，C，D
According to me answer should be (iii) option but answer is option (ii) Can anyone explain?
根据我的回答应该是（iii）选项，但答案是选项（ii）任何人都可以解释？
1 个解决方案
#1
0
The candidate keys for the given set of functional dependencies are AB, BC and BD. Since all the attributes of the relation R are come at least once in one of the candidate keys, all of them are prime attributes. The given relation R is thus automatically in 3NF.
给定的一组功能依赖性的候选键是AB，BC和BD。由于关系R的所有属性在一个候选键中至少出现一次，所以它们都是主要属性。给定关系R因此自动地在3NF中。
Option (iii) is right. The given answer is wrong.
选项（iii）是对的。给出的答案是错误的。
#1
0
The candidate keys for the given set of functional dependencies are AB, BC and BD. Since all the attributes of the relation R are come at least once in one of the candidate keys, all of them are prime attributes. The given relation R is thus automatically in 3NF.
给定的一组功能依赖性的候选键是AB，BC和BD。由于关系R的所有属性在一个候选键中至少出现一次，所以它们都是主要属性。给定关系R因此自动地在3NF中。
Option (iii) is right. The given answer is wrong.
选项（iii）是对的。给出的答案是错误的。