mysql 查询值作为列名

CREATE TABLE sales (
    id INT AUTO_INCREMENT PRIMARY KEY,
    product VARCHAR(255),
    category VARCHAR(255),
    amount DECIMAL(10, 2)
);

SELECT 
    product,
    SUM(CASE WHEN category = 'Electronics' THEN amount ELSE 0 END) AS Electronics,
    SUM(CASE WHEN category = 'Clothing' THEN amount ELSE 0 END) AS Clothing,
    SUM(CASE WHEN category = 'Books' THEN amount ELSE 0 END) AS Books
FROM 
    sales
GROUP BY 
    product;

SELECT 
    product,
    SUM(CASE WHEN category = 'Electronics' THEN amount ELSE 0 END) AS `Electronics`,
    SUM(CASE WHEN category = 'Clothing' THEN amount ELSE 0 END) AS `Clothing`,
    SUM(CASE WHEN category = 'Books' THEN amount ELSE 0 END) AS `Books`
FROM 
    sales
GROUP BY 
    product;