CREATE TABLE staff (last_name VARCHAR(255), staff_id VARCHAR(255)); CREATE TABLE complaints (staff_id VARCHAR(255), date_complaint_raised VARCHAR(255))
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