题解 | #某宝店铺折扣率#

基础的sql聚合函数
select
  round(
    sum(st.sales_price) * 100 / sum(pt.tag_price * st.sales_num) ,
    2
  ) discount_rate
from
  sales_tb st
  left join product_tb pt on pt.item_id = st.item_id