Given the following schema: employees(emp-id, first-name, last-name,…

Answer: The query executes and gives the correct result.

Explanation:

• The subquery SELECT dept-id, MAX(hire-date) FROM employees JOIN departments USING(dept-id) WHERE location-id =1700 GROUP BY dept-id returns one pair (dept-id, max_hire_date) for each department located at 1700.

• The outer WHERE (dept-id, hire-date) IN ( ... ) performs a row-value comparison: it selects employees whose department and hire-date match one of those (dept-id, max_hire_date) pairs, so the latest hire(s) per department are returned.

• If multiple employees in a department share the same maximum hire-date, all of them will be returned because their (dept-id, hire-date) pair matches the subquery result.

• Portability note: row-value IN comparisons are supported by Oracle and many SQL dialects. If you are using a DBMS that does not support row constructors, rewrite the logic using EXISTS or a join with an aggregated subquery.

Alternative (correlated subquery) if row-value comparisons are not supported:

SELECT e.last_name, e.hire_date FROM employees e WHERE e.hire_date = (SELECT MAX(e2.hire_date) FROM employees e2 WHERE e2.dept_id = e.dept_id) AND EXISTS (SELECT 1 FROM departments d WHERE d.dept_id = e.dept_id AND d.location_id = 1700);

Alternative (join with aggregated subquery):

SELECT e.last_name, e.hire_date FROM employees e JOIN (SELECT dept_id, MAX(hire_date) AS max_hire FROM employees GROUP BY dept_id) m ON e.dept_id = m.dept_id AND e.hire_date = m.max_hire JOIN departments d ON e.dept_id = d.dept_id WHERE d.location_id = 1700;

Summary: The original query is valid and returns the latest hires per department at location 1700. Use the alternatives shown when your SQL dialect does not permit row-value comparisons.