프로그래머스 - 조회수가 가장 많은 중고거래 게시판의 첨부파일 조회하기

내풀이

SELECT CONCAT('/home/grep/src/', A.BOARD_ID, '/', FILE_ID, FILE_NAME, FILE_EXT) AS FILE_PATH
FROM USED_GOODS_FILE A JOIN (SELECT BOARD_ID
FROM USED_GOODS_BOARD
WHERE VIEWS = (SELECT MAX(VIEWS)
FROM USED_GOODS_BOARD)) B ON A.BOARD_ID = B.BOARD_ID
ORDER BY A.FILE_ID DESC

• select를 3번 쓴게 좀 걸리긴한다.

다른풀이

SELECT
    CONCAT('/home/grep/src/', FILE.BOARD_ID, '/', FILE_ID, FILE_NAME, FILE_EXT) AS FILE_PATH
FROM USED_GOODS_FILE AS FILE
LEFT JOIN USED_GOODS_BOARD AS BOARD
ON FILE.BOARD_ID = BOARD.BOARD_ID
WHERE VIEWS = (SELECT MAX(VIEWS) FROM USED_GOODS_BOARD)
ORDER BY FILE_ID DESC