Databases · SQL
Official IIT answer key · IIT Kharagpur · Audited Aug 2026
GATE CSE 2014 Set 3 Q54 · MCQ · 2 marks
employee(empId, empName, empDept)customer(custId, custName, salesRepId, rating)salesRepId is a foreign key referring to empId of the employee relation. Assume that each employee makes a sale to at least one customer. What does the following query return?
SELECT empName
FROM employee E
WHERE NOT EXISTS (SELECT custId
FROM customer C
WHERE C.salesRepId = E.empId
AND C.rating <> 'GOOD');Key concept
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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 →Consider the following relational schema: employee(empId, empName, empDept) customer(custId, custName, salesRepId, rating) salesRepId is a foreign key referring to empId of the employee relation. Assume that each employee makes a sale to at least one customer. What does the following query return? SELECT empName FROM employee E WHERE NOT EXISTS (SELECT custId FROM customer C WHERE C.salesRepId = E.empId AND C.rating <> 'GOOD');
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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.