Raghuramkrishnan

Question

R(A, B, C, D)
FD: B->C, D->A

is the following decomposition in BCNF?

R1(B, C), R2(A, D), R3(C, D)

Comments

if suppose we have dependency A->B, B->C, C->D and D-> A then according to this A,B,C and D all are the keys. and we don't require any extra decomposition. So it means above statement should be incorrect.

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Yes, it dependents on the decomposition.

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@aditi19 yes... 

Answer 1

No due to lossy the decomposion is not in BCNF.

for decomposition to be a loss less the common attribute between the decompossed relation must be the candidate key of any of the decompossed relation.