https://school.programmers.co.kr/learn/courses/30/lessons/164668
SELECT USED_GOODS_USER.USER_ID, USED_GOODS_USER.NICKNAME, SUM(USED_GOODS_BOARD.PRICE) AS TOTAL_SALES
FROM USED_GOODS_USER
INNER JOIN USED_GOODS_BOARD
ON USED_GOODS_BOARD.WRITER_ID = USED_GOODS_USER.USER_ID
WHERE USED_GOODS_BOARD.STATUS = 'DONE'
GROUP BY USED_GOODS_USER.USER_ID, USED_GOODS_USER.NICKNAME
HAVING TOTAL_SALES >= 700000
ORDER BY TOTAL_SALES