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Consider a relation R related to 7 entities E1,E2…..E7 respectively, each of them has 2 attributes (A,B) (C,D) (E,F) (G,H) (I,J) (K,L) (M,N) with first attribute as candidate key in all entities. All entities are related to R with one-one mapping. What is the number of candidate keys possible for R :
  • a)
    1
  • b)
    6
  • c)
    7
  • d)
    9
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
Consider a relation R related to 7 entities E1,E2…..E7 respectively, ...
For one to one mapping b/w a relation & entity set
No. of candidate keys at R = {A.C} i.e. 2
Therefore for a relation related to 7 entities
No. of candidate keys = 7 {A, C, E, G, I, K, M}
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Most Upvoted Answer
Consider a relation R related to 7 entities E1,E2…..E7 respectively, ...
Given Information:
- There are 7 entities: E1, E2, E3, E4, E5, E6, E7.
- Each entity has 2 attributes: (A, B), (C, D), (E, F), (G, H), (I, J), (K, L), (M, N).
- The first attribute in each entity is a candidate key.
- All entities are related to relation R with a one-one mapping.

Explanation:
To find the number of candidate keys possible for relation R, we need to consider the candidate keys from each entity and take their union.

Candidate Keys from each entity:
- Entity E1: Candidate Key = A
- Entity E2: Candidate Key = C
- Entity E3: Candidate Key = E
- Entity E4: Candidate Key = G
- Entity E5: Candidate Key = I
- Entity E6: Candidate Key = K
- Entity E7: Candidate Key = M

Union of Candidate Keys:
The union of all candidate keys from each entity will give us the candidate keys for relation R.

Candidate Keys for R = {A, C, E, G, I, K, M}

Conclusion:
There are 7 candidate keys possible for relation R. Therefore, the correct answer is option 'C'.
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Consider a relation R related to 7 entities E1,E2…..E7 respectively, each of them has 2 attributes (A,B) (C,D) (E,F) (G,H) (I,J) (K,L) (M,N) with first attribute as candidate key in all entities. All entities are related to R with one-one mapping. What is the number of candidate keys possible for R :a)1b)6c)7d)9Correct answer is option 'C'. Can you explain this answer?
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Consider a relation R related to 7 entities E1,E2…..E7 respectively, each of them has 2 attributes (A,B) (C,D) (E,F) (G,H) (I,J) (K,L) (M,N) with first attribute as candidate key in all entities. All entities are related to R with one-one mapping. What is the number of candidate keys possible for R :a)1b)6c)7d)9Correct answer is option 'C'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about Consider a relation R related to 7 entities E1,E2…..E7 respectively, each of them has 2 attributes (A,B) (C,D) (E,F) (G,H) (I,J) (K,L) (M,N) with first attribute as candidate key in all entities. All entities are related to R with one-one mapping. What is the number of candidate keys possible for R :a)1b)6c)7d)9Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider a relation R related to 7 entities E1,E2…..E7 respectively, each of them has 2 attributes (A,B) (C,D) (E,F) (G,H) (I,J) (K,L) (M,N) with first attribute as candidate key in all entities. All entities are related to R with one-one mapping. What is the number of candidate keys possible for R :a)1b)6c)7d)9Correct answer is option 'C'. Can you explain this answer?.
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