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题解 | #平均播放进度大于60%的视频类别#
SELECT tag, CONCAT(ROUND(AVG(IF(TIMESTAMPDIFF(second,start_time,end_time)>duration,1,  ...
Mysql
2022-05-20
0
139
题解 | #各个视频的平均完播率#
select video_id, round(count(case when end_time-start_time >= duration the...
Mysql
2022-05-19
0
235
题解 | #统计复旦用户8月练题情况#
select distinct device_id, university, count(question_id) as question_cnt, sum( case when result = 'right' then 1 else 0 end) as right_question_cnt fr...
Mysql
2022-05-17
0
200
题解 | #浙江大学用户题目回答情况#
select device_id,question_id,result from question_practice_detail join user_profile using (device_id) where university ='浙江大学' 当两个表的列名称一致时,用using()会比较...
Mysql
2022-05-13
0
143