Database: customer_complaints
Question: Find the last name of the staff member who processed the complaint of the cheapest product.
SQL:
SELECT t1.last_name FROM staff AS t1 JOIN complaints AS t2 ON t1.staff_id  =  t2.staff_id JOIN products AS t3 ON t2.product_id  =  t3.product_id ORDER BY t3.product_price LIMIT 1