Consider the following statements regarding key – (I) A super key is an…
2022
Consider the following statements regarding key – (I) A super key is an attribute or combination of attributes that uniquely identifies records in a RDBMS table. (II) A candidate key is a subset of a super key. (III) All super keys are candidate keys but vice versa is not true.
- A.
Only (I) is true
- B.
Only (II) is true
- C.
(I) and (III) are true
- D.
(I) and (II) are true
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Correct answer: D
Statement (I) is correct because a super key uniquely identifies records in a table. Statement (II) is correct because a candidate key is a minimal super key (subset of a super key). Statement (III) is incorrect because all candidate keys are super keys, not all super keys are candidate keys. Hence, the correct option is (D).