mysql 分月查询

SELECT 
    YEAR(order_date) AS order_year,
    MONTH(order_date) AS order_month,
    COUNT(*) AS total_orders
FROM 
    orders
GROUP BY 
    YEAR(order_date), 
    MONTH(order_date)
ORDER BY 
    order_year, 
    order_month;

SELECT 
    m.year_month,
    COALESCE(SUM(o.total_orders), 0) AS total_orders
FROM 
    (SELECT DISTINCT YEAR(order_date) AS year, MONTH(order_date) AS month, CONCAT(YEAR(order_date), '-', LPAD(MONTH(order_date), 2, '0')) AS year_month FROM orders) m
LEFT JOIN 
    (SELECT YEAR(order_date) AS year, MONTH(order_date) AS month, COUNT(*) AS total_orders FROM orders GROUP BY YEAR(order_date), MONTH(order_date)) o
ON 
    m.year = o.year AND m.month = o.month
ORDER BY 
    m.year_month;