题解 | 电商平台需要对各行业销售情况综合评估

-- 逻辑拆解：按照行业分组，聚合求销售额
SELECT
    t1.industry,
    SUM(t2.sale_amount) total_sales_amount
FROM merchants_underline t1
LEFT JOIN sales_underline t2
ON t1.merchant_id = t2.merchant_id
GROUP BY t1.industry
ORDER BY total_sales_amount DESC,t1.industry