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Every BCNF decomposition is

A)Dependency preserving

B)not a dependency preserving

C)Need not be dependency preserving

D)None of the above
in Databases by (229 points) | 578 views

7 Answers

+1 vote
While every BCNF Decomposition may yield Dependency Preservation, others may not. I m not able to suggest you an appropriate option. However the link mentioned under might just clear some of your doubts. Hope it Helps. Do refer it once. :)

http://www.cs.sfu.ca/CourseCentral/354/zaiane/material/notes/Chapter7/node10.html
by Boss (13.8k points)
+1 vote

OPTION C

BCNF need not be FD preserving always. It may be or may not be.

by (439 points)
+1 vote
C)Need not be dependency preserving
by (21 points)
0 votes

Option C will be right option for it bcz every table in BCNF should not be in FDs preserving but it is not case of 3NF.This is very -very important difference in 3NF as well as BCNF.

by Boss (10.2k points)
0 votes

Need Not be Dependency Preserving.

Lossless decomposition is the fundamental thing which each and every normalization should follow.

But Preserving dependencies is followed till 2NF,3NF. But when we go for higher normalization like BCNF then  preserving the functional dependencies became difficult since the rule for BCNF are more Strict than 3NF.

by Active (1.2k points)
0 votes
Option C is the best ans.
Because in case of BCNF dependency preserving is not necessary . it may be preserved or not.
But in case of 3 nf Dependency preserving is necessary
by (413 points)
0 votes
The answer is c:

Every BCNF decomposition may or may not be dependency preserving

but remember, it will always be lossless decomposition..
by (37 points)
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