mysql列转行

CREATE TABLE sales (
    product_id INT,
    product_name VARCHAR(50),
    sales_q1 INT,
    sales_q2 INT,
    sales_q3 INT,
    sales_q4 INT
);

SELECT 
    product_id,
    product_name,
    'Q1' AS quarter,
    sales_q1 AS sales
FROM sales
UNION ALL
SELECT 
    product_id,
    product_name,
    'Q2' AS quarter,
    sales_q2 AS sales
FROM sales
UNION ALL
SELECT 
    product_id,
    product_name,
    'Q3' AS quarter,
    sales_q3 AS sales
FROM sales
UNION ALL
SELECT 
    product_id,
    product_name,
    'Q4' AS quarter,
    sales_q4 AS sales
FROM sales;

SELECT 
    product_id,
    product_name,
    'Q1' AS quarter,
    sales_q1 AS sales
FROM sales
UNION
SELECT 
    product_id,
    product_name,
    'Q2' AS quarter,
    sales_q2 AS sales
FROM sales
UNION
SELECT 
    product_id,
    product_name,
    'Q3' AS quarter,
    sales_q3 AS sales
FROM sales
UNION
SELECT 
    product_id,
    product_name,
    'Q4' AS quarter,
    sales_q4 AS sales
FROM sales;