SELECT
    LINE_ID AS LINE,
    SEAT_F,
    SEAT_T
FROM (
    SELECT
        LINE_ID,
        LAG(SEAT_NO, 2) OVER(PARTITION BY LINE_ID ORDER BY SEAT_NO) AS SEAT_F,
        SEAT_NO AS SEAT_T
    FROM SEAT_RESERVE
    WHERE RSV_STATUS = '0'
)
WHERE SEAT_F IS NOT NULL
AND SEAT_T - SEAT_F = 2
ORDER BY LINE_ID DESC, SEAT_F ASC