题解 | #获取指定客户每月的消费额#

select
    left (t_time, 7) as time,
    sum(t_amount) as total
from
    (
        select
            t.*,
            c.*
        from
            trade as t
            inner join customer as c on t.t_cus = c.c_id
        where
            c_name = "Tom"
            and year (t_time) = 2023
            and t_type = 1
    ) tmp
group by
    left (t_time, 7)
order by
    time