MySQL AUTO_INCREMENT 사용법

CREATE TABLE t_user(
user_code int NOT NULL AUTO_INCREMENT PRIMARY KEY,
user_name VARCHAR(20),
user_id VARCHAR(30),
user_password VARCHAR(300),
user_email VARCHAR(30) ,
user_registeration_date VARCHAR(30),
user_class VARCHAR(20) ,
user_image_path VARCHAR(300),
user_authority VARCHAR(30)
);

또는

CREATE TABLE t_test(
user_code int(10) NOT NULL AUTO_INCREMENT,
user_name varchar(20),
primary key(user_code)
);