1661. Average Time of Process per Machine

• 문제
  
• 정답

SELECT A1.machine_id, ROUND(AVG(A2.timestamp - A1.timestamp), 3) processing_time
FROM Activity A1 JOIN Activity A2 ON A1.machine_id = A2.machine_id AND A1.process_id=A2.process_id
WHERE A1.activity_type = 'start' AND A2.activity_type = 'end'
GROUP BY 1

• 결과