CREATE TABLE users (
  id INT(11) NOT NULL AUTO_INCREMENT,
  name VARCHAR(50) NOT NULL,
  email VARCHAR(100) NOT NULL,
  PRIMARY KEY (id)
);

CREATE TABLE users_audit (
  id INT(11) NOT NULL AUTO_INCREMENT,
  user_id INT(11) NOT NULL,
  column_name VARCHAR(50) NOT NULL,
  old_value VARCHAR(100),
  new_value VARCHAR(100),
  changed_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (id)
);

DELIMITER CREATE TRIGGER users_au
  AFTER UPDATE ON users
  FOR EACH ROW
BEGIN
  IF NEW.name != OLD.name THEN
    INSERT INTO users_audit (user_id, column_name, old_value, new_value)
    VALUES (OLD.id, 'name', OLD.name, NEW.name);
  END IF;
END

DELIMITER ;

INSERT INTO users (name, email) VALUES ('John', 'john@example.com');

UPDATE users SET name = 'Tom' WHERE id = 1;