[프로그래머스 SQL고득점 키트 JOIN]주문량이 많은 아이스크림들 조회하기

SELECT A.FLAVOR
FROM (
    SELECT FLAVOR, SUM(TOTAL_ORDER) AS S
    FROM FIRST_HALF
    GROUP BY FLAVOR) A
JOIN (
    SELECT FLAVOR, SUM(TOTAL_ORDER) AS S
    FROM JULY
    GROUP BY FLAVOR
) B
ON A.FLAVOR=B.FLAVOR
ORDER BY(A.S+B.S) DESC
LIMIT 3;