查询截止到每个月的销售额。 -- 查询结果字段： -- 月份截止当前的累计销售额自关连查询

SELECT DATE_FORMAT(s1.order_date, '%Y-%m') AS month, SUM(s2.total_amount) AS cumulative_sales FROM sales s1 JOIN sales s2 ON DATE_FORMAT(s1.order_date, '%Y-%m') >= DATE_FORMAT(s2.order_date, '%Y-%m') GROUP BY DATE_FORMAT(s1.order_date, '%Y-%m') ORDER BY month;