Database-Management-System
August 29, 2024Database-Management-System
August 29, 2024Database-Management-System
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Question 283
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Given relations R(w, x) and S(y,z), the result of select distinct w, x from R, S is guaranteed to be same as R, Provided
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R and S have no duplicates
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S has no duplicates and R is non-empty
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R and S have the same number of tuples
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R has no duplicates and S is non-empty
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Question 283 Explanation:
A)Lets assume that S is empty(no duplicates) and R is not empty then RXS will be empty which will not be equal to R.Hence false.
B)Same reason as (A) .Hence false.
C)Lets assume R has duplicates,in this case,due to distinct keyword those duplicates will get eliminated in final result and the output will not be same as R.Hence false.
D)True.From above all options explaination we can conclude this as the answer.
B)Same reason as (A) .Hence false.
C)Lets assume R has duplicates,in this case,due to distinct keyword those duplicates will get eliminated in final result and the output will not be same as R.Hence false.
D)True.From above all options explaination we can conclude this as the answer.
Correct Answer: D
Question 283 Explanation:
A)Lets assume that S is empty(no duplicates) and R is not empty then RXS will be empty which will not be equal to R.Hence false.
B)Same reason as (A) .Hence false.
C)Lets assume R has duplicates,in this case,due to distinct keyword those duplicates will get eliminated in final result and the output will not be same as R.Hence false.
D)True.From above all options explaination we can conclude this as the answer.
B)Same reason as (A) .Hence false.
C)Lets assume R has duplicates,in this case,due to distinct keyword those duplicates will get eliminated in final result and the output will not be same as R.Hence false.
D)True.From above all options explaination we can conclude this as the answer.
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