Suppose R is a relation with attributes A1 A2 An As a func

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Suppose R is a relation with attributes A_1, A_2, ....., A_n As a function of n, tell how many superkeys R has, if: The only key is A1.

Solution

The super keys of the relation R are any subset that contains A1. Hence, there are 2(n-1) such subsets, as each of the n-1 attributes A2 through An may independently be selected in or out.