SELECT
LINE_ID as LINE,
seat_no-2 as seat_F,
lag2 as SEAT_T
from(

SELECT
LINE_ID,
rsv_status,
seat_no,
lag(seat_no,1) over(partition by LINE_ID,RSV_STATUS order by SEAT_NO) +1 lag1,
lag(seat_no,2)  over(partition by LINE_ID,RSV_STATUS order by SEAT_NO) +2 lag2
FROM SEAT_RESERVE
WHERE rsv_status = '0'
)
where SEAT_NO =lag1 and lag1 = lag2
order by line desc,seat_F asc