DBMS-Function Dependency and Decomposition Questions and Answers

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Q11
Decomposition helps in eliminating some of the problems of bad design such as
  • A redundancy
  • B inconsistencies
  • C anomalies
  • D all of these
Answer: Option D
Q12
The word loss in lossless refers to the
  • A loss of information.
  • B loss of attributes
  • C loss of relations
  • D none of these.
Answer: Option A
Q13
The dependency preservation decomposition is a property of decomposed relational database schema D in which each functional dependency D----->Y specified in F
  • A appeared directly in one of the relation schemas R1 in the deomposed D.
  • B could be inferred from dependencies that appear in some Ri.
  • C both (a) and (b)
  • D none of these.
Answer: Option C
Q14
The set of attributes X will be fully functionally dependent on the set of attributes Y if the following conditions are satisfied:
  • A X is functionally dependent on Y.
  • B X is not functionally dependent on any subset of Y.
  • C both (a) and (b)
  • D none of these
Answer: Option C
Q15
Which of the following best defines a functional dependency in DBMS?
  • A A relationship between two tables
  • B Explanation: A functional dependency specifies a constraint where one set of attributes uniquely determines another set.
  • C A rule that defines primary keys only
  • D A dependency between tuples
Answer: Option B
Explanation: A functional dependency specifies a constraint where one set of attributes uniquely determines another set.
Q16
If A → B holds, it means:
  • A B determines A
  • B A and B are independent
  • C Explanation: A → B means the value of A determines the value of B.
  • D A and B must be primary keys
Answer: Option C
Explanation: A → B means the value of A determines the value of B.
Q17
Which of the following is a trivial functional dependency?
  • A A → B
  • B AB → C
  • C Explanation: A functional dependency is trivial if the right-hand side is a subset of the left-hand side.
  • D B → A
Answer: Option C
Explanation: A functional dependency is trivial if the right-hand side is a subset of the left-hand side.
Q18
Which rule states that if A → B then A → BC also holds?
  • A Transitivity
  • B Reflexivity
  • C Explanation: Augmentation allows adding attributes to both sides of a dependency.
  • D Decomposition
Answer: Option C
Explanation: Augmentation allows adding attributes to both sides of a dependency.
Q19
Which of the following is NOT an Armstrong’s axiom?
  • A Reflexivity
  • B Transitivity
  • C Explanation: Union is a derived rule, not a basic Armstrong axiom.
  • D Augmentation
Answer: Option C
Explanation: Union is a derived rule, not a basic Armstrong axiom.
Q20
If A → B and B → C, then A → C is derived using:
  • A Augmentation
  • B Reflexivity
  • C Explanation: Transitivity allows inference of indirect dependencies.
  • D Decomposition
Answer: Option C
Explanation: Transitivity allows inference of indirect dependencies.

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