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题解 | #异常的邮件概率#

select date,round(sum(case when type='no_completed' then 1 else 0 end)/count(type),3) as p from email where send_id in (select id from user where is_...

Mysql

2021-09-19

2 537

题解 | #出现三次以上相同积分的情况#

select t.number from (select *,rank()over(order by number) as rank2 from grade) t group by t.rank2 having count(1)>=3 先用窗口函数对积分进行排名，相同的积分名次相同。再以排...

Mysql

2021-09-18

1 446

题解 | #对于employees表中，给出奇数行的first_name#

select e.first_name from employees e join (select first_name,row_number()over(order by first_name) as rank2 from employees) t on e.first_name=t.first...

Mysql

2021-09-18

0 386