Test by Bikram | Mock GATE | Test 3 | Question: 25

Question

Consider these relations :

$R = ABCDE$

$A\rightarrow BC$
$B\rightarrow E$
$D\rightarrow E$

What is the candidate key for the above relations?

• A. CA
• B. AB
• C. BD
• D. AD

Answer 1

we can solve it by verifying options.

Option A) $(CA)^+\rightarrow CABE$

Option B) $(AB)^+\rightarrow AB\rightarrow ABC\rightarrow ABCE$

Option C) $(BD)^+\rightarrow BDE$

Option D) $(AD)^+\rightarrow ABD\rightarrow ABCD\rightarrow ABCDE $

So this option covers all the attributes, unlike others.

Option (D) is correct.