DBMS-Function Dependency and Decomposition Questions and Answers
DBMS Function Dependency and Decomposition questions with answers focus on understanding the relationship between attributes in a relational database. Functional dependency plays a crucial role in normalization, ensuring data consistency and reducing redundancy. Practicing aptitude questions and answers with explanations on this topic helps you strengthen your DBMS fundamentals. These aptitude test practice questions are commonly asked in competitive exams like GATE and placement tests by TCS, Wipro, and Infosys. Learning through solved DBMS questions with solutions PDF enhances your conceptual clarity for both academic and job interviews.
DBMS-Function Dependency and Decomposition
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39 questions
31. Which normal form may sacrifice dependency preservation?
- 2NF
- 3NF
- Explanation: BCNF decomposition may not preserve all dependencies.
- 1NF
32. A minimal cover of functional dependencies has:
- Redundant dependencies
- Explanation: Minimal cover requires RHS to have a single attribute.
- Composite attributes on RHS
- No dependencies
33. Which of the following is NOT a requirement of minimal cover?
- No redundant dependencies
- Single attribute RHS
- No extraneous attributes
- Explanation: Minimal cover is independent of normal forms.
34. An attribute is extraneous if:
- It is part of primary key
- Explanation: Removing an extraneous attribute does not change dependency closure.
- It appears only on RHS
- It is non-prime
35. Which of the following is a prime attribute?
- Attribute not in any key
- Explanation: Prime attributes are part of candidate keys.
- Attribute in primary key only
- Attribute with unique values
36. In 3NF, for a dependency X → A, which condition is acceptable?
- X must be a super key
- A must be prime
- Explanation: 3NF allows dependency if X is super key or A is prime.
- Neither a nor b
37. Which operation splits a relation into smaller relations?
- Union
- Selection
- Explanation: Decomposition divides a relation into two or more relations.
- Projection
38. Which dependency cannot be inferred from Armstrong’s axioms?
- Reflexive
- Transitive
- Union
- Explanation: All functional dependencies can be derived using Armstrong’s axioms and derived rules.
39. Why is normalization mainly performed?
- To increase redundancy
- To improve query speed
- Explanation: Normalization reduces redundancy and prevents update anomalies.
- To increase table size