SELECT
    line_id AS line,
    seat_no -1 AS seat_f,
    seat_no + 1 AS seat_t
FROM (
    SELECT
        line_id,
        seat_no,
        -- LAG(seat_no, 1) OVER(PARTITION BY line_id ORDER BY seat_no),
        seat_no - LAG(seat_no, 1) OVER(PARTITION BY line_id ORDER BY seat_no) AS lag_seat,
        seat_no - LEAD(seat_no, 1) OVER(PARTITION BY line_id ORDER BY seat_no) AS lead_seat
    FROM seat_reserve
    WHERE rsv_status = 0
)
WHERE lag_seat=1 AND lead_seat=-1
ORDER BY line_id DESC, seat_f