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A relation R(Student, Course) contains the tuples (A, DB), (A, OS), (A, CN), (B, DB), (B, OS), (C, DB), (C, OS), (C, CN), (C, AI), (D, CN).…

2349Medium DSSSB TGT Computer Science 0 replies 1 views

A relation R(Student, Course) contains the tuples (A, DB), (A, OS), (A, CN), (B, DB), (B, OS), (C, DB), (C, OS), (C, CN), (C, AI), (D, CN). The relation S(Course) contains DB, OS and CN. Which students appear in the result of R ÷ S?

AA and C
BA, B and C
CC only
DA, C and D

Correct answer: A

Explanation

Division returns the students associated with every course of S; only A and C are enrolled in DB, OS and CN together.

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