题解 | #每月各旬有多少人练题#

with cte as (
select left(event_date,7) as dt_month,
        case when right(event_date,2)<=9  then '上旬'
             when right(event_date,2)<=19 then '中旬'
             else '下旬' end as dt_days ,count(distinct device_id) as cnt
from question_practice_detail 
group by  dt_month,dt_days )
select concat(left(dt_month,4),'年',mid(dt_month,6,2),'月',dt_days) as dt_range,cnt
from cte 
order by dt_month desc,cnt desc