Neco 2025 Computer Studies Question 23

Practice objective / multiple choice question 23 from the 2025 Neco Computer Studies examination.

Neco 2025 Computer Studies Objective / Multiple Choice Hard Difficulty

Question 23 NECO • 2025 • COMPUTER_STUDIES • objective

Let \(R(A,B,C)\) and \(S(B,D)\) be two relations. Consider the relational‑algebra query: \[ \pi_{A,D}\bigl(\sigma_{C>10}(R) \;\bowtie_{R.B = S.B}\; \sigma_{D<5}(S)\bigr) \] Rewrite the query so that selections and projections are applied as early as possible, thereby minimising the size of intermediate results. Provide the equivalent expression.

A. π_{A,D}( (π_{A,B}(σ_{C>10}(R))) ⨝_{R.B = S.B} (π_{B,D}(σ_{D<5}(S))) )

B. π_{A,D}( (π_{A,C}(σ_{C>10}(R))) ⨝_{B = B} (π_{B,D}(σ_{D<5}(S))) )

C. π_{A,D}( (π_{A,B}(σ_{C>10}(R))) ⨝_{B = B} (σ_{D<5}(S)) )

Correct Answer D. π_{A,D}( (π_{A,B}(σ_{C>10}(R))) ⨝_{B = B} (π_{B,D}(σ_{D<5}(S))) )

Correct Answer

Correct Option:

π_{A,D}( (π_{A,B}(σ_{C>10}(R))) ⨝_{B = B} (π_{B,D}(σ_{D<5}(S))) )

This is Neco 2025 Computer Studies Question 23. It is one of the objective questions from the 2025 Neco Computer Studies examination.

Difficulty level: Hard .

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