sql用戶留存率

 每天的7日用戶留存情況，從一段時間用戶第一次登陸算起的留存情況

SELECT
    first_day,
    sum(case when by_day = 0 then 1 else 0 end) day_0,
    sum(case when by_day = 1 then 1 else 0 end) day_1,
    sum(case when by_day = 2 then 1 else 0 end) day_2,
    sum(case when by_day = 3 then 1 else 0 end) day_3,
    sum(case when by_day = 4 then 1 else 0 end) day_4,
    sum(case when by_day = 5 then 1 else 0 end) day_5,
    sum(case when by_day = 6 then 1 else 0 end) day_6,
    sum(case when by_day >= 7 then 1 else 0 end) day_7plus
FROM
   (SELECT 
      user_id,
      login_time,
      first_day,
      DATEDIFF(login_time,first_day) as by_day
   FROM
     (SELECT
        b.user_id,
        b.login_time,
        c.first_day
      FROM 
        (SELECT
            user_id,
            str_to_date(login_time,'%Y/%m/%d') login_time
         FROM user_info
         GROUP BY 1,2) b
    LEFT JOIN
      (SELECT
          user_id,
          min(login_time) first_day
       FROM
           (select 
                user_id,
                str_to_date(login_time,'%Y/%m/%d') login_time
            FROM 
                user_info
            group by 1,2) a
       group by 1) c
     on b.user_id = c.user_id
     order by 1,2) e
  order by 1,2) f
group by 1
order by 1

最終的樣子