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

WITH temp AS(    
    SELECT a.brand_id,b.brand_name,a.return_status,c.customer_satisfaction_score
    FROM sales_orders AS a
    INNER JOIN brand_info AS b ON a.brand_id = b.brand_id
    INNER JOIN customer_feedback AS c ON a.order_id = c.order_id
    WHERE MONTH(a.order_date) = 7
)

SELECT brand_id,brand_name,
round(avg(return_status),2) return_rate_July_2024,
round(avg(customer_satisfaction_score),2) average_customer_satisfaction_score
FROM temp 
GROUP BY brand_id,brand_name
ORDER BY brand_id ASC

以sales_order为表连结的主表，因为剩下两个表没办法直接相连，我第一遍就犯了这个错误,剩下的就简单了,GROUP BY 或者窗口函数都可以