WITH A AS (
    SELECT LINE_ID LINE
          ,SEAT_NO SEAT_F
          ,SEAT_NO + 2 SEAT_T
          ,(SELECT RSV_STATUS FROM SEAT_RESERVE WHERE LINE_ID = SR.LINE_ID AND SEAT_NO = SR.SEAT_NO) RN1
          ,(SELECT RSV_STATUS FROM SEAT_RESERVE WHERE LINE_ID = SR.LINE_ID AND SEAT_NO = SR.SEAT_NO + 1) RN2
          ,(SELECT RSV_STATUS FROM SEAT_RESERVE WHERE LINE_ID = SR.LINE_ID AND SEAT_NO = SR.SEAT_NO + 2) RN3
      FROM SEAT_RESERVE SR
     ORDER BY SR.LINE_ID DESC
             ,SR.SEAT_NO
)
SELECT LINE
      ,SEAT_F
      ,SEAT_T
  FROM A
 WHERE RN1 = 0
   AND RN2 = 0
   AND RN3 = 0
 ORDER BY LINE DESC
         ,SEAT_F