看着好像没有加入时间限定条件得，加了一个12月下旬where条件

select round(sum(sale_sum),3) as sales_total,
round(sum(sale_sum) / count(distinct user_id),3) as per_trans
from
(
select s.goods_id,user_id,goods_name,
(sales_num*goods_price) as sale_sum from sales_tb as s 
left join goods_tb as g on s.goods_id = g.goods_id
where sales_date between '2021-12-21' and '2021-12-31'
) as t