Kerala PSC AP Exam

Question

Consider a relation R with five attributes V,W,X,Y and Z. The following functional dependencies hold : $VY \rightarrow W, WX \rightarrow Z$ and $VY \rightarrow W, WX \rightarrow Z$ and  ZY \rightarrow V$. Which of the following is a candidate key for R

A) VXZ

B) VXY

C) VWXY

D) VWXYZ

Answer 1

Candidate key will be B.VXY

Since X is not identified by other attributes so it definitely would be included in candidate key.. and VY uniquely identifies W.. and further WX would uniquely identify Z.. since Candidate key is minimal set which identify each attribute uniquely.. So VXY would be candidate key.