Database-Management-System
August 29, 2024Transactions
August 29, 2024Database-Management-System
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Question 606
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Division operation is ideally suited to handle queries of the type :
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customers who have no account in any of the branches in Delhi.
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customers who have an account at all branches in Delhi.
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customers who have an account in at least one branch in Delhi.
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customers who have only joint account in any one branch in Delhi
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Question 606 Explanation:
→ The DIVISION operation is defined for convenience for dealing with queries that involve universal quantification or the all condition. For a tuple ‘t’ to appear in the result T of the DIVISION, the values in ‘t’ must appear in R in combination with every tuple in S.
→ Note that in the formulation of the DIVISION operation, the tuples in the denominator relation S restrict the numerator relation R by selecting those tuples in the result that match all values
present in the denominator. The DIVISION operation can be expressed as a sequence of π, ×, and – operations as follows:
T1 ← πY(R)
T2 ← πY((S × T1) – R)
T ← T1 – T2
→ Note that in the formulation of the DIVISION operation, the tuples in the denominator relation S restrict the numerator relation R by selecting those tuples in the result that match all values
present in the denominator. The DIVISION operation can be expressed as a sequence of π, ×, and – operations as follows:
T1 ← πY(R)
T2 ← πY((S × T1) – R)
T ← T1 – T2
Correct Answer: B
Question 606 Explanation:
→ The DIVISION operation is defined for convenience for dealing with queries that involve universal quantification or the all condition. For a tuple ‘t’ to appear in the result T of the DIVISION, the values in ‘t’ must appear in R in combination with every tuple in S.
→ Note that in the formulation of the DIVISION operation, the tuples in the denominator relation S restrict the numerator relation R by selecting those tuples in the result that match all values
present in the denominator. The DIVISION operation can be expressed as a sequence of π, ×, and – operations as follows:
T1 ← πY(R)
T2 ← πY((S × T1) – R)
T ← T1 – T2
→ Note that in the formulation of the DIVISION operation, the tuples in the denominator relation S restrict the numerator relation R by selecting those tuples in the result that match all values
present in the denominator. The DIVISION operation can be expressed as a sequence of π, ×, and – operations as follows:
T1 ← πY(R)
T2 ← πY((S × T1) – R)
T ← T1 – T2