UGC NET CSE | August 2016 | Part 3 | Question: 10

Question

Consider the table $R$ with attributes $A, B$ and $C$. The functional dependencies that hold on $R$ are : $A \rightarrow B, C \rightarrow AB$. Which of the following statements is/are True ?

I. The decomposition of $R$ into $R1(C, A)$ and $R2(A, B)$ is lossless.

II. The decomposition of $R$ into $R1(A, B)$ and $R2(B, C)$ is lossy.

• A. Only $I$
• B. Only $II$
• C. Both $I$ and $II$
• D. Neither $I$ nor $II$

Answer 1

1.R1(C,A) R1(A,B)

R1∩R2 =A which is super key for A

so its lossless join .

2.R1(A,B) R1(B,C)

R1∩R2=B which is not super key for any relation so its lossy join .

BOTH are correct

(C) OPTION ANS .