WITH tmp as (

SELECT
LINE_ID LINE,
seat_no,
min(seat_no) over (partition by line_id order by seat_no asc rows between 1 PRECEDING
AND 1 PRECEDING ) as prec,
min(seat_no) over (partition by line_id order by seat_no asc rows between 1 FOLLOWING
AND 1 FOLLOWING ) as fol
from SEAT_RESERVE


)
select t.line LINE,
t.prec SEAT_F,
t.fol SEAT_T
from  tmp t
where 
exists (select 1  from SEAT_RESERVE sr where sr.line_id=t.line and sr.seat_no = t.seat_no and sr.RSV_STATUS='0')
and
exists (select 1  from SEAT_RESERVE sr where sr.line_id=t.line and  sr.seat_no = t.prec and sr.RSV_STATUS='0')
and
exists (select 1  from SEAT_RESERVE sr where sr.line_id=t.line and  sr.seat_no = t.fol and sr.RSV_STATUS='0')

order by 
LINE desc,
SEAT_F asc