참고 : https://lsj-1991.tistory.com/28 https://dev-comsj.tistory.com/entry/MySQL-%EC%B4%88%EB%8B%B9-%EA%B1%B4%EC%88%98-%EC%A1%B0%ED%9A%8C-%EC%8B%9C%EA%B0%84%EB%8B%B9-%EB%8D%B0%EC%9D%B4%ED%84%B0%EB%B3%84-%EC%A1%B0%ED%9A%8C-%ED%86%B5%EA%B3%84
