mysql添加主键列

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

ALTER TABLE users ADD PRIMARY KEY (id);

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

INSERT INTO users_new (id, name, email)
SELECT id, name, email FROM users;

DROP TABLE users;
RENAME TABLE users_new TO users;

INSERT IGNORE INTO users (id, name, email) VALUES (1, 'Alice', 'alice@example.com');

INSERT INTO users (id, name, email) VALUES (1, 'Alice', 'alice@example.com')
ON DUPLICATE KEY UPDATE name = 'Alice', email = 'alice@example.com';