2026-08-01

1 SQL31

select
 
    day(date) as day,
 
    count(question_id) as question_cnt
 
from
 
    question_practice_detail
 
where
 
    year(date) = 2021
 
    and month(date) = 8
 
group by
 
    date

2 SQL32

select
 
    round(count(q2.date)/count(q1.date), 4) as avg_ret
 
from
 
    (select distinct device_id, date from question_practice_detail) q1
 
left join
 
    (select distinct device_id, date from question_practice_detail) q2
 
on
 
    q1.device_id = q2.device_id
 
    and q2.date = date_add(q1.date, interval 1 day)

3 SQL33

select
 
    substring_index(profile, ",", -1) as gender,
 
    count(device_id) as number
 
from
 
    user_submit
 
group by
 
    gender

4 输入法测试

从前