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(if(type='no_completed',1,0))/count(id),3) p from email where send_id not in (select id black_id from user where is_blacklist='1') and receive_id not in (select id black_id from user where is_blacklist='1') group by date order by date;