mysql实现按年月分组

CREATE TABLE sales (
    id INT AUTO_INCREMENT PRIMARY KEY,
    amount DECIMAL(10, 2),
    sale_date DATE
);

SELECT YEAR(sale_date) AS year, SUM(amount) AS total_amount
FROM sales
GROUP BY YEAR(sale_date)
ORDER BY year;

SELECT YEAR(sale_date) AS year, MONTH(sale_date) AS month, SUM(amount) AS total_amount
FROM sales
GROUP BY YEAR(sale_date), MONTH(sale_date)
ORDER BY year, month;

SELECT YEAR(sale_date) AS year, MONTH(sale_date) AS month, SUM(amount) AS total_amount
FROM sales
GROUP BY YEAR(sale_date), MONTH(sale_date)
ORDER BY year, month;

ALTER TABLE sales MODIFY COLUMN sale_date DATE;

SELECT YEAR(sale_date) AS year, MONTH(sale_date) AS month, SUM(amount) AS total_amount
FROM sales
WHERE sale_date IS NOT NULL AND sale_date != ''
GROUP BY YEAR(sale_date), MONTH(sale_date)
ORDER BY year, month;