题解 | 获取指定客户每月的消费额

select date_format(tr.t_time,"%Y-%m")as time,
sum(tr.t_amount)  as total
from trade as tr
left join customer as cus on tr.t_cus=cus.c_id
where cus.c_name='Tom' and year(tr.t_time)='2023' and tr.t_type = '1'
group by time,month(tr.t_time)
order by month(tr.t_time)