Multiple choice

R, (A, B, C, D) is a relation. Which of the following does not have a lossless join, dependency preserving BCNF decomposition?

  1. A $\rightarrow$ B, B $\rightarrow$ CD
  2. A $\rightarrow$ B, B $\rightarrow$ C, C $\rightarrow$ D
  3. AB $\rightarrow$ C, C $\rightarrow$ AD
  4. A $\rightarrow$ BCD
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

R(A,B,C,D) In options (1) & (2) there exists transitive functional dependency, so incorrect for BCNF. In option (3) AB $\rightarrow$ C C $\rightarrow$ AD So        AB $\rightarrow$ AD B $\rightarrow$ D In option (4) all the attributes depend on the same key in BCNF.

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