Return the first names of the 5 staff members who have handled the most complaints.
SELECT t1.first_name FROM staff AS t1 JOIN complaints AS t2 ON t1.staff_id  =  t2.staff_id GROUP BY t2.staff_id ORDER BY count(*) LIMIT 5
SELECT t1.first_name FROM staff AS t1 JOIN complaints AS t2 ON t1.staff_id  =  t2.staff_id GROUP BY t2.staff_id ORDER BY count(*) LIMIT 5
[{'first_name': 'Dagmar'}, {'first_name': 'Bradly'}, {'first_name': 'Austin'}, {'first_name': 'Lucie'}, {'first_name': 'Mikel'}]