select round(sum(ps),3) as sales_total,round(sum(ps)/sum(count_1),3) as per_trans from 
(
select user_id,sum(goods_price*sales_num) as ps, 1 as count_1 from 
(select s.goods_id as goods_id,user_id,sales_num,goods_price from sales_tb as s
join(
select goods_id,goods_price from goods_tb 
) as g
on s.goods_id = g.goods_id) as t1
group by user_id) as t2