mysql 按年月统计

SELECT 
    YEAR(order_date) AS year,
    MONTH(order_date) AS month,
    COUNT(*) AS order_count
FROM 
    orders
GROUP BY 
    YEAR(order_date), MONTH(order_date)
ORDER BY 
    year, month;

SELECT 
    YEAR(order_date) AS year,
    MONTH(order_date) AS month,
    COUNT(*) AS order_count
FROM 
    orders
WHERE 
    order_date IS NOT NULL AND order_date != ''
GROUP BY 
    YEAR(order_date), MONTH(order_date)
ORDER BY 
    year, month;

CREATE INDEX idx_order_date ON orders(order_date);

SELECT 
    COALESCE(YEAR(order_date), 0) AS year,
    COALESCE(MONTH(order_date), 0) AS month,
    COUNT(*) AS order_count
FROM 
    orders
GROUP BY 
    YEAR(order_date), MONTH(order_date)
ORDER BY 
    year, month;