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Question

An instance of relational schema R (A, B, C) has distinct values of A including NULL values. Which one of the following is true?

a.

A is a candidate key

b.

A is not a candidate key

c.

A is a primary Key

d.

Both a and c

Posted under The Entity Relationship Approach DBMS

Answer: (b).A is not a candidate key

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Q. An instance of relational schema R (A, B, C) has distinct values of A including NULL values. Which one of the following is true?
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