DSSSB TGT 2021
January 28, 2024DSSSB TGT 2021
January 28, 2024GATE 2001
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Question 25
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Let r and s be two relations over the relation schemes R and S respectively, and let A be an attribute in R. Then the relational algebra expression σA=a(r⋈s) is always equal to
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σA=a (r)
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r
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σA=a (r)⨝s
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None of the above
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Question 25 Explanation:
(a) A=a for all r
(b) Display table
(c) A=a for all Tables r and s
(b) Display table
(c) A=a for all Tables r and s
Correct Answer: C
Question 25 Explanation:
(a) A=a for all r
(b) Display table
(c) A=a for all Tables r and s
(b) Display table
(c) A=a for all Tables r and s