Transaction related Query to display two immediate transaction time difference

Transaction related Query to display two immediate transaction time difference

SELECT *

FROM
(
SELECT mt.transnumber
      ,LEAD(mt.transnumber, 1, 1) OVER (PARTITION BY TRNTYPE ORDER BY id) next_transnumber
      ,mt.trntype 
      ,mt.modifiedtimestamp transaction_time
      ,LEAD(mt.modifiedtimestamp, 1, SYSDATE) OVER (PARTITION BY TRNTYPE ORDER BY id)  next_transaction_time
      ,floor(((LEAD(mt.modifiedtimestamp, 1, SYSDATE) OVER (PARTITION BY TRNTYPE ORDER BY id) - mt.modifiedtimestamp)*24*60*60)/3600) time_diff
  FROM mastertxn mt 
WHERE trntype = 'TOPUP' 
ORDER BY ID
)
WHERE time_diff >= 1


//Output pattern
                                                                                        
TRANSNUMBER  NEXT_TRANSNUMBER TRNTYPE    TRANSACTION_TIME      NEXT_TRANSACTION_TIME    TIME_DIFF 
1244           1360            TOPUP     05.10.2010 23:58:39   07.10.2010 10:48:43        34
1360           1408            TOPUP     07.10.2010 10:48:43   07.10.2010 16:34:55         5
1442           1507            TOPUP     07.10.2010 19:19:33   08.10.2010 11:26:43        16