题解 | 获取指定客户每月的消费额

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

注意区分消费金额和转账。