UGC NET CSE | June 2023 | Part 2: 19

Question

Let $\text{R (A,B,C,D,E,F)}$ be a relational schema with following functional dependencies:
$\mathrm{C} \rightarrow \mathrm{F}, \mathrm{E} \rightarrow \mathrm{A}, \mathrm{EC} \rightarrow \mathrm{D}, \mathrm{A} \rightarrow \mathrm{B}$. Which of the following is a key for $\mathrm{R}$ ?

• A. $\text{CD}$
• B. $\text{EC}$
• C. $\mathrm{AE}$
• D. $\mathrm{AC}$

Answer 1

Will use closure property to check all the options :

CD+ = {C,D,F}

EC+ = {E,C,F,A,D,B}

AE+ = {A,E,B}

AC+ = {A,C,F,B}

Ans : Option B – EC.