mysql 一行变为一列

CREATE TABLE students (
    id INT PRIMARY KEY,
    name VARCHAR(50),
    age INT,
    grade VARCHAR(10)
);

SELECT id AS info FROM students WHERE id = 1
UNION ALL
SELECT name AS info FROM students WHERE id = 1
UNION ALL
SELECT age AS info FROM students WHERE id = 1
UNION ALL
SELECT grade AS info FROM students WHERE id = 1;

SELECT
    CASE WHEN @row_number := @row_number + 1 = 1 THEN id END AS info,
    CASE WHEN @row_number = 2 THEN name END AS info,
    CASE WHEN @row_number = 3 THEN age END AS info,
    CASE WHEN @row_number = 4 THEN grade END AS info
FROM students, (SELECT @row_number := 0) AS t
WHERE id = 1;

SELECT id AS info FROM students WHERE id = 1
UNION
SELECT name AS info FROM students WHERE id = 1
UNION
SELECT age AS info FROM students WHERE id = 1
UNION
SELECT grade AS info FROM students WHERE id = 1;

SELECT
    CASE WHEN @row_number := @row_number + 1 = 1 THEN id END AS info,
    CASE WHEN @row_number = 2 THEN name END AS info,
    CASE WHEN @row_number = 3 THEN age END AS info,
    CASE WHEN @row_number = 4 THEN grade END AS info
FROM students, (SELECT @row_number := 0) AS t
WHERE id = 1
ORDER BY @row_number;