mysql 更新复合表

CREATE TABLE users (
    user_id INT,
    username VARCHAR(50),
    email VARCHAR(100),
    age INT,
    PRIMARY KEY (user_id, username)
);

UPDATE users
SET age = 30, email = 'newemail@example.com'
WHERE user_id = 1 AND username = 'john_doe';

-- 错误的SQL示例
UPDATE users SET age = 30, email = 'newemail@example.com' WHERE user_id = 1;

-- 正确的SQL示例
UPDATE users SET age = 30, email = 'newemail@example.com' WHERE user_id = 1 AND username = 'john_doe';

START TRANSACTION;

UPDATE users SET age = 30, email = 'newemail@example.com' WHERE user_id = 1 AND username = 'john_doe';

COMMIT;

-- 检查用户权限
SHOW GRANTS FOR 'current_user'@'localhost';

-- 授予权限
GRANT UPDATE ON database_name.users TO 'current_user'@'localhost';