mysql语句求百分比

SELECT 
    product,
    quantity,
    (quantity / total_quantity) * 100 AS percentage
FROM (
    SELECT 
        product,
        quantity,
        (SELECT SUM(quantity) FROM sales) AS total_quantity
    FROM sales
) AS subquery;

SELECT 
    product,
    quantity,
    ROUND((quantity / total_quantity) * 100, 2) AS percentage
FROM (
    SELECT 
        product,
        quantity,
        (SELECT SUM(quantity) FROM sales) AS total_quantity
    FROM sales
) AS subquery;

SELECT 
    product,
    quantity,
    IF(total_quantity > 0, (quantity / total_quantity) * 100, 0) AS percentage
FROM (
    SELECT 
        product,
        quantity,
        (SELECT SUM(quantity) FROM sales) AS total_quantity
    FROM sales
) AS subquery;