题解 | 查询出每个品牌在特定时间段内的退货率以及平均客户满意度评分

--连接表，聚合函数和case判断
select 
bf.brand_id,
bf.brand_name,
round(
sum(case when return_status=1 then 1 else 0 end)/count(sd.order_id),2) as return_rate_July_2024,
round(
avg(customer_satisfaction_score),2) as average_customer_satisfaction_score

from customer_feedback ck inner join 
sales_orders sd  on ck.order_id=sd.order_id
inner join brand_info bf on bf.brand_id=sd.brand_id
where
date_format(order_date,"%Y%m")=202407
group by bf.brand_id
order by bf.brand_id