Task: Text to Code
Input (English): Step 1: For each row in Staff table, find the corresponding rows in Complaints table.
Step 2: find the number of rows of each value of Complaints's staff_id in the results of step 1.
Step 3: find last_name of step 1 results with smallest value in the results of step 2
Output (English): SELECT T1.last_name FROM Staff AS T1 JOIN Complaints AS T2 ON T1.staff_id = T2.staff_id GROUP BY T2.staff_id ORDER BY Count ( * ) Asc LIMIT 1