题解 | #异常的邮件概率#
异常的邮件概率
http://www.nowcoder.com/practice/d6dd656483b545159d3aa89b4c26004e
select date,
round(sum(case type when 'completed' then 0 else 1 end)*1.0/count(type),3)
from email
where send_id not in (select id from user where is_blacklist=1)
and receive_id not in (select id from user where is_blacklist=1)
group by date
order by date;
