Given the following relation R with 5 attributes and the three functional dependencies shown, which of the following is true?

Select one answer.

Question

Given the following relation R with 5 attributes and the three functional dependencies shown, which of the following is true?

Select one answer.

BlackTom AI · Accepted Answer

The question presents a relation R with attributes A, B, C, D, E and asks which statement about the given functional dependencies is true.
Option to evaluate: { A,B } → C is a full functional dependency.
First, recall what a full functional dependency means: a dependency X → Y is full if Y depends on the entire set X and not on any proper subset of X. In other words, removing any attribute from X should destroy the dependency if that attribute is essential for determining Y.
Now, consider the specific dependency { A,B } → C. To determine if this is full, we must check whether A → C or B → C (i.e., dependencies with a proper subset of {A,B} as the determinant) hold or not.
- If A → C held, then C would be determined by A alone, meaning AB → C would not be a full FD (it would be a partial FD because part of the determinant suffices).
- If B → C held, similarly AB → C would not be full for the same reason.
Since the diagram indicates that C is determined by the combination of A and B and there is no indication that either A alone or B alone determines C, the dependency { A,B } → C is a candidate for a full FD.
In contrast, if the given set of FDs included A → C or B → C, one of those would violate the “full” condition for AB → C. Without such a subset dependency present, AB → C remains full.
Therefore, the statement { A,B } → C is a full functional dependency is consistent with the idea that the determinant must be the whole {A,B} set and not reducible to a proper subset.
Note: if the data or diagram had shown A → C or B → C as true, the conclusion would change, and {A,B} → C would be classified as partial instead. The correctness hinges on whether A → C or B → C are implied by the provided FDs, which the diagram does not indicate as being the case.

G6031: Databases Databases MOCK EXAM Part 1

Given the following relation R with 5 attributes and the three functional dependencies shown, which of the following is true? Select one answer.

查看解析

登录即可查看完整答案

类似问题

Every time attribute A appears, it is matched with the same value of attribute B, but not the same value of attribute C. Therefore, it is true that:

Using the Entity Relationship Diagram you have drawn on your piece of paper for the Hamilton Island 'BoatRaceResults' Table, answer the following question. Which functional dependency shows a Transitive Dependency in the BoatRaceResults table?

Using the Entity Relationship Diagram you have drawn on your piece of paper for the Hamilton Island 'BoatRaceResults' Table, answer the following question. Which attribute is fully Dependent on the primary key of the BoatRaceResults table?

Using the Entity Relationship Diagram you have drawn on your piece of paper for the Hamilton Island 'BoatRaceResults' Table, answer the following question. Which are Dependent Non-Key Attributes of the BoatRaceResults table?

You are given this relation: A B C a1 b1 c5 a1 b2 c6 a2 b1 c7 a3 b2 c6 A possible candidate key is: [ Select ] , and a functional dependency is: [ Select ]

Because of the need to know the functional dependencies in a database, it is a good idea to create a(n) ________.

Because of the need to know the functional dependencies in a database, it is a good idea to create a(n) ________.

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单