1.将两个表用left join基于up.device_id = qpd.device_id左连接，提取复旦大学用户；2.按照device_id分组；3.按照条件用sum函数统计练题总数和正确数，重命名。 select up.device_id, university, sum(if (month(date)=8, 1, 0)) question_cnt, sum(if (result = 'right', 1, 0)) right_question_cnt from user_profile up left join question_practice_detail qpd on up.de...
