题解 | 用户每日登录后次3日内活跃天数
select a.id, count(b.id) from user_visit_log a left join user_visit_log b on a.id = b.id and timestampdiff (day, a.visit_date, b.visit_date) < 3 and timestampdiff (day, a.visit_date, b.visit_date) >= 1 group by a.id order by a.id
