mysql 给数据加序号

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50),
    email VARCHAR(50)
);

SELECT 
    @row_number := @row_number + 1 AS row_number,
    name,
    email
FROM 
    users, (SELECT @row_number := 0) AS t
ORDER BY 
    id;

SELECT 
    ROW_NUMBER() OVER (ORDER BY id) AS row_number,
    name,
    email
FROM 
    users;

SELECT 
    t.row_number,
    t.name,
    t.email
FROM 
    (
        SELECT 
            @row_number := @row_number + 1 AS row_number,
            name,
            email
        FROM 
            users, (SELECT @row_number := 0) AS t
        ORDER BY 
            id
        LIMIT 10 OFFSET 20
    ) AS t;