题解 | 电商平台需要对商家的销售业绩、退款情况和客户满意度进行综合评估

select
t1.merchant_id merchant_id
,merchant_name
,total_sales_amount
,total_refund_amount
,average_satisfaction_score
from 
(select
merchant_id
,merchant_name
from merchants_underline) t1
join 
(select 
merchant_id
,sum(sale_amount) total_sales_amount
from sales_underline
group by merchant_id) t2 on t1.merchant_id = t2.merchant_id
join
(select 
merchant_id
,round(avg(satisfaction_score),2) average_satisfaction_score
from satisfaction_underline
group by merchant_id) t3 on t1.merchant_id = t3.merchant_id
join
(select 
merchant_id
,sum(refund_amount) total_refund_amount
from refunds_underline
group by merchant_id) t4 on t1.merchant_id = t4.merchant_id
order by merchant_id