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Databases · SQL
Official IIT answer key · IIT Kanpur · Audited Aug 2026
GATE CSE 2015 Set 1 Q27 · NAT · 2 marks
SELECT S.Student_Name, sum(P.Marks)
FROM Student S, Performance P
WHERE S.Roll_No = P.Roll_No
GROUP BY S.Student_Name
The number of rows that will be returned by the SQL query is ____________.
Key concept
Topic notes
In GATE CS, SQL is tested through a balanced mix of declarative query semantics, relational-algebra correspondence, subquery evaluation (correlated, nested, and universal quantification), and instance-level tracing. Questions range from conceptual integrity rules (DDL constraints, FOREIGN KEY targets, GROUP BY/HAVING rules) to practical computation of output row counts and aggregate values on small database instances. Recent papers strongly emphasize NAT execution traces and multi-correct (MSQ) equivalent query formulations.
Full SQL guide →Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.