题解 | #每月各旬有多少人练题#
每月各旬有多少人练题
https://www.nowcoder.com/practice/48c8bef6528d4d838e9646682e2b395d
select ( concat( concat(substr(event_date,1,4),'年'), concat(substr(event_date,6,2),'月'), ( case when day(event_date)<=9 then '上旬' when day(event_date)>9 and day(event_date)<=19 then '中旬' when day(event_date)>=20 then '下旬' end))) dt_range, count(distinct device_id) as cnt from question_practice_detail group by dt_range order by substr(dt_range,6,2) desc, cnt desc
写连接起来有点小复杂,其实理清楚了,也没啥。