一步一步来吧。 确定每个用户最早出现的日期,即每个用户作为新用户时的日期 select user_id, min(date) as first_date from login group by user_id 基于step1结果确定每个新用户次日留存了的记录。用right join留存了则保留次日日期,未留存则为None select b.user_id, b.first_date, a.date from login as a right join ( select user_id, min(date) as first_date from login group b...