กิจกรรมตามชั่วโมงของวัน ไม่จำเป็นต้องใช้ทุกตาราง
Activity by hour of day.It is not neccessary to use all the tables.
 ReviewTasks:  Id [ number]  ReviewTaskTypeId [ number]  CreationDate [ time]  DeletionDate [ time]  ReviewTaskStateId [ number]  PostId [ number]  SuggestedEditId [ number]  CompletedByReviewTaskId [ number] 
SELECT TIME_TO_STR(CreationDate, '%h'), 'Questions', COUNT(*) FROM Posts WHERE PostTypeId = 1 GROUP BY TIME_TO_STR(CreationDate, '%h') UNION SELECT TIME_TO_STR(CreationDate, '%h'), 'Answers', COUNT(*) FROM Posts WHERE PostTypeId = 2 GROUP BY TIME_TO_STR(CreationDate, '%h') UNION SELECT TIME_TO_STR(CreationDate, '%h'), 'Comments/3', COUNT(*) / 3 FROM Comments GROUP BY TIME_TO_STR(CreationDate, '%h') UNION SELECT TIME_TO_STR(CreationDate, '%h'), 'Post Events/5', COUNT(*) / 5 FROM PostHistory GROUP BY TIME_TO_STR(CreationDate, '%h')