https://inpa.tistory.com/entry/MYSQL-%F0%9F%93%9A-%EC%9B%8C%ED%81%AC%EB%B2%A4%EC%B9%98%EC%97%90%EC%84%9C-%ED%85%8C%EC%9D%B4%EB%B8%94-ERD-%EC%83%9D%EC%84%B1%ED%95%98%EA%B8%B0
