题解 | #获取指定客户每月的消费额#

# 现需要查询 Tom 这个客户在 2023 年每月的消费金额（按月份正序显示）

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