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:

Question

BlackTom AI · Accepted Answer

The statement describes a functional dependency pattern between attributes: whenever A occurs, it is paired with the same B value (A -> B), while the C value can vary.
Option 1: '(B, C) --> A' would mean that the pair (B, C) determines A. The given rule only asserts A determines B and allows C to vary with A; it does not claim that knowing B and C together uniquely identifies A. Therefore this option is not supported by the description.
Option 2: 'A --> B' matches the described behavior: each time A appears, B has the same value, establishing a functional dependency from A to B. This is precisely what the statement conveys, so this option aligns with the given rule.
Option 3: 'A --> C' would claim that A uniquely determines C. The original sentence explicitly states that C does not have a fixed value with A (it can be different), so asserting A -> C contradicts the provided information.
Option 4: 'A --> (B, C)' would mean A determines both B and C together. Since C can vary with A according to the description, A does not determine a single value of C; thus this broader dependency is not correct given the stated variability of C.
Taken together, the only dependency that faithfully represents the described relationship is the direct A --> B option, while the others imply fixed or combined determinations that the statement does not support.

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:

查看解析

登录即可查看完整答案

类似问题

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 ]

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

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