with seat as (
    select
        LINE_ID as LINE,
        SEAT_NO as SEAT_F,
        SEAT_NO + 1 as SEAT_S,
        SEAT_NO + 2 as SEAT_T
    from SEAT_RESERVE
    where
        SEAT_T <= 15
)
select
    LINE,
    SEAT_F,
    SEAT_T
from seat
where
    (select RSV_STATUS from SEAT_RESERVE as sr where LINE = LINE_ID and SEAT_F = SEAT_NO ) = '0' and
    (select RSV_STATUS from SEAT_RESERVE as sr where LINE = LINE_ID and SEAT_S = SEAT_NO ) = '0' and
    (select RSV_STATUS from SEAT_RESERVE as sr where LINE = LINE_ID and SEAT_T = SEAT_NO ) = '0'
order by
    LINE desc,
    SEAT_F asc
;