用户刷题情况:用户的名字，以及截止到某天，累计总通过了多少题

select
    name u_n,
    date,
    sum(number) over(partition by user_id order by date) ps_num
from login l
left join passing_number p using(user_id,date)
left join user u on l.user_id=u.id
where number is not null
order by date,u_n

/*

select 
    u.name u_n,
    date,
    sum(number) over(partition by user_id order by date)
from passing_number p
left join user u on p.user_id=u.id
order by date,u_n

*/