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1 vote
1 vote

Maximum number of superkeys for the relation schema $R(X,Y,Z,W)$ with $X$ as the key is

  1. $6$
  2. $8$
  3. $9$
  4. $12$
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3 Answers

4 votes
4 votes
Maximum number of super keys are 8 because X is a key and if any one is included with key it will be a super key.

We have two choices for each one (Y,Z,W) include it and don't include it. making it as 2^3=8

Correct answer is B
2 votes
2 votes
We know that definatly a X is a super key. So from pending Y,Z,W maximum number of super keys can be $2^3 - 1 = 7$ and As X is a key then 7+1 = 8 is max number of super key
1 vote
1 vote
Maximum no. of possible superkeys for a table with n attributes = 2^(n-1)
Here, n = 4.
So, the possible superkeys = 2^(4-1) = 2^3 = 8
The possible superkeys are : X, XY, XZ, XW, XYZ, XYW, XWZ, XYZW

1 comment

It is incorrect explanation
correct explaination: We know that definatly a X is a super key. So from pending Y,Z,W maximum number of super keys can be $2^3 - 1 = 7$ and As X is a key then 7+1 = 8 is max number of super key
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