select start_month,
        count(distinct uid) mau,sum(new) month_add_uv,
        max(sum(new)) over(order by start_month ),
        SUM(sum(new))OVER(ORDER BY start_month) cum_sum_uv
from(
    select *,date_format(start_time,'%Y%m') start_month,
    if(start_time=(min(start_time) over(partition by uid)),1,0) new
    from exam_record
    ) t1
group by start_month

思路：

1.每月用户活跃数：按月分组，distinct(uid)

2.每月新增用户数：新增一列标记每个用户是否为第一次登录，是为1，不是为0。

if(start_time=(min(start_time) over(partition by uid)),1,0)

按月分组进行加和

3.截至当月单月最大新增用户数：截至当月新增用户数最大值 max(sum(new)) over(order by start_month )

4.截至当月累计用户数：每个月的新增人数相加