题解 | #异常的邮件概率#
异常的邮件概率
https://www.nowcoder.com/practice/d6dd656483b545159d3aa89b4c26004e
#sum(type = "no_completed") / count(*) 等价于 sum(case when type = "no_completed" then 1 else 0 end) / count(*) select date, round(sum(type = "no_completed") / count(*), 3) as p from email as t1 join user as t2 on t1.send_id = t2.id join user as t3 on t1.receive_id = t3.id where t2.is_blacklist = 0 and t3.is_blacklist = 0 group by date order by date;