MadeEasy Subject Test: Databases - Candidate Keys

Question

Answer 1

There is a slight misprint in the solution otherwise option D is correct

For a superkey you need to make sure that it contains one of the candidate key :

2^m ways are there to pick up one of the m keys but it also includes the choice when none of them is choosen so we need to subtract that case (2^m-1)

 Rest of prime attributes may or may not be picked, So 2^n-m ways.

By rule of counting:

Total ways : (2^m-1).(2^n-m )

Comments

thnx