Question 9763 – Database-Management-System

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 σ_A=a(r⋈s) is always equal to

Correct Answer: C

Question 46 Explanation:

(a) A=a for all r
(b) Display table
(c) A=a for all Tables r and s

σ_A=a (r)

σ_A=a (r)⨝s

None of the above

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