题解 | 获取指定客户每月的消费额

select date_format(t.t_time, '%Y-%m') as time,
sum(t_amount) as total
from trade t
join customer c 
on t.t_cus = c.c_id
where c.c_name = 'Tom' and year(t.t_time) = '2023'
and t.t_type = 1
group by date_format(t.t_time, '%Y-%m')
order by time