3 votes 3 votes Databases database-normalization + – Shefali asked Oct 10, 2015 Shefali 1.6k views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes I think we can decompose to BCNF but it will violate the dependency preserving. Here AC is the candidate key BCNF decomposition R1(ABC) (AC is the candidate key ) R2(BCD) (BC+ is the candidate key) R3(DE) ( D+=DE D is the candidate key) AC->BC BC->D D->E Further no decomposition is possible ! I guess. So option B Umang Raman answered Oct 10, 2015 Umang Raman comment Share Follow See all 14 Comments See all 14 14 Comments reply Show 11 previous comments vineet.ildm commented Sep 23, 2017 reply Follow Share @arjun sir after directly applying bcnf decomposition algorithm for this question we will not get dependency preservation. but 3nf decomposition gives decompositions which are also in bcnf. so if we get bcnf decompositions from 3nf decomposition can we answer yes for such question? 0 votes 0 votes Arjun commented Sep 23, 2017 reply Follow Share No, In your decomposition, you get AC->D, FD and also A->B. And when you take closure, this covers BC->D. So, it is dependency preserving -- you might be applying the dependency check wrongly. 0 votes 0 votes jiminpark commented Jan 13, 2022 reply Follow Share @vineet.ildm Sir , I am getting the same decomposition as yours. So is it wrong? @Arjun Sir, please tell if it will dependancy preserving / not ? because the 3NF form decomposition is also lossless. 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes Ans should be yes..!! R1(A,B) R2(A,C) R3(B,C,D) R4(D,E) rishu_darkshadow answered Sep 21, 2017 rishu_darkshadow comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes Answer is option b: NO Cannot decompose into BCNF without violating Functional Dependency Preservation. Varun Raj Akula answered Jan 22, 2022 Varun Raj Akula comment Share Follow See all 0 reply Please log in or register to add a comment.