with cte  as (select 
LINE_ID
,SEAT_NO
,sum(RSV_STATUS) over ww as b
,count() over ww as c
from
SEAT_RESERVE
window ww as (partition by LINE_ID order by SEAT_NO ROWS BETWEEN CURRENT ROW AND 2 FOLLOWING)

)
select
LINE_ID as LINE
,SEAT_NO as SEAT_F
,SEAT_NO+2 as SEAT_T
from cte where b=0 and c=3
order by
LINE desc
,SEAT_F