题解 | #出现三次以上相同积分的情况#
异常的邮件概率
http://www.nowcoder.com/practice/d6dd656483b545159d3aa89b4c26004e
where 竟然可以并列判断 哈哈哈学到了
select t1.date, round(no_completed/count_completed,3) p from ( select date, count(*) count_completed, sum(if(type='no_completed',1,0)) no_completed from email where send_id and receive_id not in (select id from user where is_blacklist=1) group by date )t1