SELECT MAX(PRICE) AS MAX_PRICE FROM PRODUCT;
SELECT PRICE AS MAX_PRICE FROM( SELECT PRICE FROM PRODUCT ORDER BY PRICE DESC) WHERE ROWNUM = 1;
MAX 함수와 MIN 함수 https://gent.tistory.com/420 서브쿼리 잘 활용하는게 굉장히 중요할 듯...