题解 | #异常的邮件概率#

难题——首先需要找出正常用户（正常发送用户、正常接收用户），然后统计失败的概率； 解题代码：

select email.date,round(sum(case email.type when 'completed' then 0
                           else 1
                           end ) *1.0/count(email.type),3) as p
from email 
join user as u1 on (email.send_id=u1.id and u1.is_blacklist=0)
join user as u2 on (email.receive_id=u2.id and u2.is_blacklist=0)
group by email.date
order by email.date