题解 | #获取指定客户每月的消费额#

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