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题解 | #大小写混乱时的筛选统计#

select e.tag, count(c.id) from exam_record c, examination_info d, ( select b.tag from exam_record a, examination_info b where a.exam_id=b.exa...

2023-09-03

0 153

题解 | #对过长的昵称截取处理#

select uid, case when char_length(nick_name)>13 then concat(left(nick_name,10),'...') else nick_name end nick_name from user_info where char_leng...

2023-09-03

0 174

题解 | #修复串列了的记录#

select exam_id, substring_index(tag,',',1) tag, substring_index(substring_index(tag,',',2),',',-1) diffifulty, substring_index(tag,',',-1) duration fr...

2023-09-03

0 159

题解 | #每个6/7级用户活跃情况#

select a.uid, count(distinct date_format(b.start_time,'%Y%m')) act_month_total, count(distinct case when year(b.start_time)='2021' then date_format(...

2023-09-03

0 232

题解 | #满足条件的用户的试卷完成数和题目练习数#

select a.uid, count(distinct a.id) exam_cnt, count(distinct b.id) question_cnt -- select * from exam_record a left join practice_record b on a.uid=...

2023-09-03

0 180

题解 | #分别满足两个活动的人#

select distinct uid, 'activity1' activity from exam_record where score is not null and uid not in ( select uid from exam_record where s...

2023-09-02

0 142

题解 | #分别满足两个活动的人#

select distinct uid, 'activity1' activity from exam_record where score is not null and uid not in ( select uid from exam_record where s...

2023-09-02

0 145

题解 | #每个题目和每份试卷被作答的人数和次数#

select tid, uv, pv from ( select exam_id tid, count(distinct uid) uv, count(exam_id) pv from exam_record group by exam_id order by uv desc,pv ...

2023-09-02

0 221

题解 | #作答试卷得分大于过80的人的用户等级分布#

select c.level, count(c.level) level_cnt from exam_record a, examination_info b, user_info c where a.exam_id=b.exam_id and a.uid=c.uid and b.tag='SQ...

2023-09-02

0 230

题解 | #试卷发布当天作答人数和平均分#

select b.exam_id, count(distinct b.uid) uv, format(sum(b.score) /count( b.uid),1) avg_score from examination_info a, exam_record b, user_info c wh...

2023-09-02

0 213