1
$\begingroup$

I have a schema R = {A,B,C,D,E} and the set F of FDs:

F = {A --> BCDE, CD --> E, EC --> B}.

Candidate key = A Non - Prime Attributes = BCDE Prime Attributes = A

According to me, there is no partial dependency because no non-prime attribute is dependent on part of CK.

E and B are transitively dependent on A so the schema Ris not in 3NF.

Decomposing R into 3NF, I have three relations and three set of FDs :

R1(A,B,C,D)                         F1={A --> B,A --> C,A --> D}
R2(C,D,E)                           F2={CD --> E}
R3(E,C,B)                           F3={EC --> B}

My question is, Is my decomposition of R into 3NF is lossless and preserving all dependencies or not? And if not how can I decompose it into 3NF losslessly while preserving all dependencies.

$\endgroup$
  • $\begingroup$ Basically you should break it in only two relations. Once you break the table to resolve CD --> E, the other transitive dependency is automatically resolved because E is no longer part of the table which has B in it. $\endgroup$ – Navjot Waraich Nov 2 '18 at 0:54
0
$\begingroup$

So My decomposition is lossless and preserving all dependencies but there is no need for relation R3(E, C, B) because we already have A which can derive B in R1.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.