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Question 64Asked in UGC NET Computer Science, June 2017 (Paper II & III, Selected Questions)

Which one is correct w.r.t. RDBMS?

  1. APrimary key ⊆ super key ⊆ candidate key
  2. BPrimary key ⊆ candidate key ⊆ super key
  3. CSuper key ⊆ candidate key ⊆ primary key
  4. DSuper key ⊆ primary key ⊆ candidate key
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Correct answer: (B) Primary key ⊆ candidate key ⊆ super key

Explanation

Super key: a set of attributes that uniquely identifies a tuple. Candidate key: a minimal super key (no proper subset is a super key). Primary key: the candidate key chosen to identify tuples. So Primary key ⊆ candidate key ⊆ super key.

From UGC NET Computer Science PYQ, June 2017 (Paper II & III, Selected Questions)

This is question 64 of UGC NET Computer Science PYQ, June 2017 (Paper II & III, Selected Questions). See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.