mysql 实现 每行累加

SELECT 
    DATE_FORMAT(bldat, '%Y-%m') AS month,
    SUM(quantity) AS monthly_quantity,
    SUM(quantity) OVER (ORDER BY DATE_FORMAT(bldat, '%Y-%m')) AS cumulative_quantity
FROM 
    sales
GROUP BY 
    DATE_FORMAT(bldat, '%Y-%m')
ORDER BY 
    month;

　　

+---------+----------------+-------------------+
| month   | monthly_quantity | cumulative_quantity |
+---------+----------------+-------------------+
| 2023-01 |             15 |                15 |
| 2023-02 |             11 |                26 |
| 2023-03 |             22 |                48 |
+---------+----------------+-------------------+