Table schema:
CREATE TABLE staff (last_name VARCHAR, staff_id VARCHAR); CREATE TABLE complaints (staff_id VARCHAR, date_complaint_raised VARCHAR)

Question: What is the last name of the staff who has handled the first ever complaint?
SQL: SELECT t1.last_name FROM staff AS t1 JOIN complaints AS t2 ON t1.staff_id = t2.staff_id ORDER BY t2.date_complaint_raised LIMIT 1