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A relation has the attributes R(ABCDEPG). The set of Functional Dependencies are :

$F: { AB \to CD, DE \to P, C\to E, P\to C, B \to G }$

After normalising this relation till 3NF, I get the following tables : ${ABDE, DP, PC, CE, and BG}$

Please confirm the answer.

The decomposition is lossless, but I am not getting dependency preserving property. However, I read it in books that IT IS ALWAYS POSSIBLE TO GET A LOSSLESS AND DEPENDENCY PRESERVING PROPERTY IN 3NF - But I am not getting the Dependency Preservation property. Is something wrong with the decomposition ?

2 Answers

Best answer
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IT IS ALWAYS POSSIBLE TO GET A LOSSLESS AND DEPENDENCY PRESERVING PROPERTY IN 3NF

it does not means, you take any decomposition i will guarantee that lossless and dependency preservation.

 

it mean there exist atleast one decomposition, which will have the lossless and dependency preservation property

 

for your question, consider these tables

ABCD

BG

DPE

PC

CE
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  • Till BCNF lossless decomposition is always possible.

  •  in dependency preseving till 3NF IT IS ALWAYS POSSIBLE .

  • But if a relation in  BCNF then dependency preserving may or may not be possible .

  • Possible mean there exist a decomposed relation which satisfy dependency preserving .
  • But your decomposed relation dosnt satisfy dependency preserving.
  • For my decomposion it is dependency preseving.

 

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