If a relation has 8 attributes and there are three simple candidate keys are possible then calculate the total number of superkeys.
(A) 224
(B) 248
(C) 256
(D) None of these.


Answer: (A)

Explanation: There are total ways to represent present (1) or absent (0) for 3 prime attributes (Boolean variables). Out of 2³ = 8, only 7 ways can have atleast one prime keys (first (000) can not have any prime attribute).

Now, there are only 5 (=8-3) non-prime attributes. These 5 prime attributes either can present (1) or absent (0). So, total possible ways are 2⁵ = 32.

Hence, total number of possible superkeys are = 7*32 = 224

So, option (A) is correct.

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