题解 | 每月各旬有多少人练题

select case when (day(event_date) between 1 and 9) then concat(year(event_date),"年",mid(event_date,6,2),"月上旬") when (day(event_date) between 10 and 19 ) then concat(year(event_date),"年",mid(event_date,6,2),"月中旬") when day(event_date)>=20 then concat(year(event_date),"年",mid(event_date,6,2),"月下旬") else "未知" end dt_range,count(distinct device_id) cnt from
question_practice_detail
group by dt_range
order by mid(dt_range,6,2) desc,cnt desc