GATE CS 2014 Set 1 — Question 64

MCQ+2 / -0.67MediumSubqueriesSQLDatabasesSQL JoinsAggregate FunctionsGrouping & Ordering

Databases → SQL → Aggregate Functions

Last updated 5 September 2026

Question

Given the following schema: employees(emp-id, first-name, last-name, hire-date, dept-id, salary) departments(dept-id, dept-name, manager-id, location-id) You want to display the last names and hire dates of all latest hires in their respective departments in the location ID 1700. You issue the following query: SQL>SELECT last-name, hire-date FROM employees WHERE (dept-id, hire-date) IN (SELECT dept-id, MAX(hire-date) FROM employees JOIN departments USING(dept-id) WHERE location-id = 1700 GROUP BY dept-id); What is the outcome?

Correct answer (B) It executes and gives the correct result. Solution The query is designed to find employees who have the maximum hire date within their department, specifically for departments in location 1700. 1. Subquery : SELECT dept-id, MAX(hire-date) FROM employees JOIN departments USING(dept-id) WHERE location-id = 1700 GROUP BY dept-id This correctly joins the tables, filters for location 1700, groups by department, and returns the department ID and the latest (MAX) hire date for that department. 2. Outer Query : SELECT last-name, hire-date FROM employees WHERE (dept-id, hire-date) IN (...) This selects the name and hire date of employees whose dept-id and hire-date match a pair returned by the subquery. This effectively selects the employee(s) who were hired on the latest date in each valid department. 3. Syntax Validity : Pairwise comparison (a, b) IN (SELECT x, y ...) is valid standard SQL. GROUP BY can be used with joins in subqueries. Therefore, the query executes successfully and produces the correct result (the latest hires in the specified departments). Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (B) It executes and gives the correct result. Solution The query is designed to find employees who have the maximum hire date within their department, specifically for departments in location 1700. 1. Subquery : SELECT dept-id, MAX(hire-date) FROM employees JOIN departments USING(dept-id) WHERE location-id = 1700 GROUP BY dept-id This correctly joins the tables, filters for location 1700, groups by department, and returns the department ID and the latest (MAX) hire date for that department. 2. Outer Query : SELECT last-name, hire-date FROM employees WHERE (dept-id, hire-date) IN (...) This selects the name and hire date of employees whose dept-id and hire-date match a pair returned by the subquery. This effectively selects the employee(s) who were hired on the latest date in each valid department. 3. Syntax Validity : Pairwise comparison (a, b) IN (SELECT x, y ...) is valid standard SQL. GROUP BY can be used with joins in subqueries. Therefore, the query executes successfully and produces the correct result (the latest hires in the specified departments).

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