DBMS · Question 13 · Hard
Relation R(A, B, C) has the single functional dependency B → C. It is decomposed into R1(A, B) and R2(B, C). Which statement is correct?
- The decomposition is lossless and dependency preserving
- It is lossy but dependency preserving
- It is lossless but not dependency preserving
- It is neither lossless nor dependency preserving
Answer and explanation
Answer: A. The decomposition is lossless and dependency preserving
Explanation: The common attribute B is a key of R2 (B → C), so the join is lossless. The only FD B → C lies entirely within R2, so the decomposition also preserves dependencies.
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