题解 | 物流公司想要分析快递小哥的收入情况

-- 逻辑拆解：先仔细查看两个表，不存在笛卡尔积陷阱，直接连接按条件求值即可
SELECT  
    t1.courier_id,t1.courier_name,t1.base_salary+SUM(t2.delivery_fee) total_income
FROM couriers_info t1
LEFT JOIN deliveries_info t2
ON t1.courier_id = t2.courier_id
WHERE delivery_date BETWEEN '2024-07-01' AND '2024-07-31' 
GROUP BY t1.courier_id
ORDER BY t1.courier_id