SELECT 
LINE_ID as LINE,
SEAT_NO as SEAT_F,
(SEAT_NO + 2) as SEAT_T
FROM (

    SELECT 
    LINE_ID ,
    SEAT_NO,
    RSV_STATUS as rsv,
    lead(RSV_STATUS,1) over(ORDER BY LINE_ID,SEAT_NO ASC) as sec_rsv,
    lead(RSV_STATUS,2) over(ORDER BY LINE_ID,SEAT_NO ASC) as thd_rsv
    
    FROM SEAT_RESERVE
)
WHERE rsv == "0" AND sec_rsv == "0" AND thd_rsv == "0"
ORDER BY LINE DESC, SEAT_F ASC