DBMS-Function Dependency and Decomposition Questions and Answers

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Q31
Which normal form may sacrifice dependency preservation?
  • A 2NF
  • B 3NF
  • C Explanation: BCNF decomposition may not preserve all dependencies.
  • D 1NF
Answer: Option C
Explanation: BCNF decomposition may not preserve all dependencies.
Q32
A minimal cover of functional dependencies has:
  • A Redundant dependencies
  • B Explanation: Minimal cover requires RHS to have a single attribute.
  • C Composite attributes on RHS
  • D No dependencies
Answer: Option B
Explanation: Minimal cover requires RHS to have a single attribute.
Q33
Which of the following is NOT a requirement of minimal cover?
  • A No redundant dependencies
  • B Single attribute RHS
  • C No extraneous attributes
  • D Explanation: Minimal cover is independent of normal forms.
Answer: Option D
Explanation: Minimal cover is independent of normal forms.
Q34
An attribute is extraneous if:
  • A It is part of primary key
  • B Explanation: Removing an extraneous attribute does not change dependency closure.
  • C It appears only on RHS
  • D It is non-prime
Answer: Option B
Explanation: Removing an extraneous attribute does not change dependency closure.
Q35
Which of the following is a prime attribute?
  • A Attribute not in any key
  • B Explanation: Prime attributes are part of candidate keys.
  • C Attribute in primary key only
  • D Attribute with unique values
Answer: Option B
Explanation: Prime attributes are part of candidate keys.
Q36
In 3NF, for a dependency X → A, which condition is acceptable?
  • A X must be a super key
  • B A must be prime
  • C Explanation: 3NF allows dependency if X is super key or A is prime.
  • D Neither a nor b
Answer: Option C
Explanation: 3NF allows dependency if X is super key or A is prime.
Q37
Which operation splits a relation into smaller relations?
  • A Union
  • B Selection
  • C Explanation: Decomposition divides a relation into two or more relations.
  • D Projection
Answer: Option C
Explanation: Decomposition divides a relation into two or more relations.
Q38
Which dependency cannot be inferred from Armstrong’s axioms?
  • A Reflexive
  • B Transitive
  • C Union
  • D Explanation: All functional dependencies can be derived using Armstrong’s axioms and derived rules.
Answer: Option D
Explanation: All functional dependencies can be derived using Armstrong’s axioms and derived rules.
Q39
Why is normalization mainly performed?
  • A To increase redundancy
  • B To improve query speed
  • C Explanation: Normalization reduces redundancy and prevents update anomalies.
  • D To increase table size
Answer: Option C
Explanation: Normalization reduces redundancy and prevents update anomalies.

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