The relational algebra expression equivalent to the following tuple calculus…
1999
The relational algebra expression equivalent to the following tuple calculus expression is:
{ t | t ∈ r ∧ (t[A] = 10 ∧ t[B] = 20) }
- A.
σ(A=10 ∨ B=20)(r)
- B.
σ(A=10)(r) ∪ σ(B=20)(r)
- C.
σ(A=10)(r) ∩ σ(B=20)(r)
- D.
σ(A=10)(r) - σ(B=20)(r)
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Correct answer: C
The tuple calculus expression selects tuples t from r such that both conditions are true: t[A] = 10 and t[B] = 20.
In relational algebra, applying both selection conditions is equivalent to selecting A = 10 and selecting B = 20, then taking the intersection of the two result sets.
Therefore, the equivalent expression is σ(A=10)(r) ∩ σ(B=20)(r).