SELECT *
  FROM (SELECT a.sql_id,
               a.sample_time,
               COUNT (*)
               OVER (PARTITION BY a.blocking_session, a.user_id, a.program)
                  cpt,
               ROW_NUMBER ()
               OVER (PARTITION BY a.blocking_session, a.user_id, a.program
                     ORDER BY blocking_session, a.user_id, a.program)
                  rn,
               a.blocking_session,
               (SELECT object_name
                FROM dba_objects
                WHERE object_id = a.current_obj#
                 AND ROWNUM < 2) object_name,
                 (SELECT dbms_ROWID.ROWID_create (
                                        1,
                                        o.data_object_id,
                                        current_file#,
                                        current_block#,
                                        current_row#
                                        ) row_id 
                FROM dba_objects o 
                WHERE data_object_id=a.current_obj# and rownum<2
                )
                 BLOCKING_SESSION_STATUS,
                  decode(session_state, 'WAITING','Waiting',
                        'Working') state,
               a.user_id,
               a.program,
               s.sql_text
          FROM sys.dba_hist_ACTIVE_SESS_HISTORY a, sys.dba_hist_sqltext s
         WHERE     a.sql_id = s.sql_id
               AND blocking_session_serial# <> 0
               AND a.user_id <> 0
           AND a.sample_time >= TO_DATE (TRIM ('1-jan-2014 00:00:00'), 'dd-mon-yyyy hh24:mi:ss')
           AND a.sample_time <= TO_DATE (TRIM ('12-jan-2014 23:00:00 '), 'dd-mon-yyyy hh24:mi:ss')
ORDER BY a.sample_time)
WHERE rn = 1