select 
    line_id as LINE, 
    seat_no - 2 as SEAT_F, 
    seat_no as SEAT_T
from 
    (
        select 
            line_id, 
            seat_no, 
            rsv_status, 
            case 
                when rsv_status = '0' and lag(rsv_status, 1) over(partition by line_id order by seat_no) = '0' and lag(rsv_status, 2) over(partition by line_id order by seat_no) = '0' then 1
                else 0
            end as status
        from 
            seat_reserve
    ) as grouped
where 
    status = 1
order by 
    LINE asc, 
    SEAT_F asc;