题解 | #异常的邮件概率#
异常的邮件概率
https://www.nowcoder.com/practice/d6dd656483b545159d3aa89b4c26004e
SELECT date, round(count(if(type="no_completed",true,null))/count(type),3) is_blacklist 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 date ORDER BY date
通过join筛选掉黑名单用户，再用countif计算出结果即可