SELECT e.first_name, e.last_name, d.dept_name, emp_hours.total_hours
FROM employees e
JOIN departments d ON e.dept_id = d.dept_id
JOIN (
  SELECT emp_id, SUM(hours) AS total_hours
  FROM project_assignments
  GROUP BY emp_id
) emp_hours ON e.emp_id = emp_hours.emp_id
WHERE emp_hours.total_hours = (
  SELECT MAX(sub.total_hours)
  FROM (
    SELECT e2.dept_id, SUM(pa2.hours) AS total_hours
    FROM employees e2
    JOIN project_assignments pa2 ON e2.emp_id = pa2.emp_id
    GROUP BY e2.emp_id, e2.dept_id
  ) sub
  WHERE sub.dept_id = e.dept_id
)
ORDER BY d.dept_name;