解决这种注册后留存，新增用户数问题，关键在于构建一个用户注册表

select r.date,sum(r.date=注册日期) from login as r join ( select user_id,min(date)as 注册日期 from login group by user_id) as t on r.user_id=t.user_id group by r.date order by r.date asc;