with tmp as(
select LINE_ID,
SEAT_NO,
Lead(SEAT_NO) over(partition by LINE_ID order by SEAT_NO) as Lead1,
Lead(SEAT_NO,2) over(partition by LINE_ID order by SEAT_NO) as Lead2
  from SEAT_RESERVE
 where RSV_STATUS = '0')
select LINE_ID as LINE,
SEAT_NO as SEAT_F,
Lead2 as  SEAT_T
  from tmp
 where Lead1 = SEAT_NO+1
   and Lead2 = SEAT_NO+2
order by LINE_ID desc,SEAT_NO asc