Avg Time Difference of Two timestamps in Oracle SQL

Question

Hello Members,
  I am trying to find the average of Time Difference of two timestamp columns by order number. I need to show the average of the time difference in hours:mins format. I have is SQL Server , but unable to get this in Oracle SQL. Could anyone please let me know how I need to find the time difference of two timestamp columns and show them in hh:mm fomat and then take average of these differences and show them in hh:mm format.  Below is what I have tried in SQL server.
CREATE TABLE temp
startdate smalldatetime,
enddate smalldatetime
INSERT temp
SELECT '6/22/2013 19:00',
'6/22/2013 19:20'
UNION ALL
SELECT '6/22/2013 19:22',
'6/22/2013 19:44'
UNION ALL
SELECT '6/22/2013 19:45',
'6/22/2013 19:50'
UNION ALL
SELECT '6/22/2013 19:52',
'6/22/2013 20:02'
UNION ALL
SELECT '6/22/2013 20:05',
'6/22/2013 20:10'
UNION ALL
SELECT '6/22/2013 20:15',
'6/22/2013 20:20'
SELECT CAST
CAST
( SUM
DATEDIFF(MINUTE,startdate,enddate)
6*60
As float)
as varchar) + ':' +
cast
cast
cast
SUM
DATEDIFF(MINUTE,startdate,enddate)
6
as int )
% 60 as float )
as varchar ) AS avg_time_diff_in_hh_mm_format
FROM temp
Please let me know if you need additional information.
Thanks in Advance.

Answer 1

Thanks for the reply Frank,
  I have tried some similar lines with your suggested approach, please see below:
--DDL
CREATE TABLE XX_ORD_TIMES
(ORDER_NUM NUMBER(15),
         ACTUAL_START_DATE DATETIME,
         ACTUAL_FINISH_DATE DATETIME)
--Sample Data
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SFM-07', TO_DATE('06/20/2013 14:22:58', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('06/21/2013 07:58:55', 'MM/DD/YYYY HH24:MI:SS'));
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SFM-07', TO_DATE('06/21/2013 09:12:42', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('06/21/2013 09:18:15', 'MM/DD/YYYY HH24:MI:SS'));
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SFM-07', TO_DATE('06/20/2013 15:59:07', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('06/20/2013 17:06:17', 'MM/DD/YYYY HH24:MI:SS'));
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SVCEXT', TO_DATE('05/16/2013 11:56:05', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('05/24/2013 14:47:54', 'MM/DD/YYYY HH24:MI:SS'));
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SVCEXT', TO_DATE('05/07/2013 09:23:37', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('05/07/2013 13:00:14', 'MM/DD/YYYY HH24:MI:SS'));
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SVCEXT', TO_DATE('05/09/2013 14:06:08', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('05/22/2013 13:25:03', 'MM/DD/YYYY HH24:MI:SS'));
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SVCNEWPLON', TO_DATE('05/21/2013 13:17:45', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('05/24/2013 14:35:04', 'MM/DD/YYYY HH24:MI:SS'));
Insert into XX_ORD_TIMES
   (ORDER_NUM, ACTUAL_START_DATE, ACTUAL_FINISH_DATE)
Values
   ('SVCNEWPLON', TO_DATE('05/24/2013 09:00:04', 'MM/DD/YYYY HH24:MI:SS'), TO_DATE('05/29/2013 09:30:32', 'MM/DD/YYYY HH24:MI:SS'));
--Avg time diffs
SELECT  ORDER_NUM,
         ACTUAL_START_DATE
         ACTUAL_FINISH_DATE
                TO_NUMBER (
                   SUBSTR (
                      NUMTODSINTERVAL (
                         AVG (
                              CAST (ACTUAL_FINISH_DATE AS DATE)
                            - CAST (ACTUAL_START_DATE AS DATE)),
                         'DAY'),
                      2,
                      9))
              * 24
            + TO_NUMBER (
                 SUBSTR (
                    NUMTODSINTERVAL (
                       AVG (
                            CAST (ACTUAL_FINISH_DATE AS DATE)
                          - CAST (ACTUAL_START_DATE AS DATE)),
                       'DAY'),
                    12,
                    2))
         || ':'
         || CASE
               WHEN LENGTH (
                       TO_NUMBER (
                          SUBSTR (
                             NUMTODSINTERVAL (
                                AVG (
                                     CAST (ACTUAL_FINISH_DATE AS DATE)
                                   - CAST (ACTUAL_START_DATE AS DATE)),
                                'DAY'),
                             15,
                             2))) < 2
               THEN
                     '0'
                  || TO_NUMBER (
                        SUBSTR (
                           NUMTODSINTERVAL (
                              AVG (
                                   CAST (ACTUAL_FINISH_DATE AS DATE)
                                 - CAST (ACTUAL_START_DATE AS DATE)),
                              'DAY'),
                           15,
                           2))
               ELSE
                  TO_CHAR (
                     SUBSTR (
                        NUMTODSINTERVAL (
                           AVG (
                                CAST (ACTUAL_FINISH_DATE AS DATE)
                              - CAST (ACTUAL_START_DATE AS DATE)),
                           'DAY'),
                        15,
                        2))
            END
            AS TIME_DIFF
    FROM XX_ORD_TIMES
   GROUP BY ORDER_NUM,
         ACTUAL_START_DATE
         ACTUAL_FINISH_DATE
         order by 1;
Yes, I am trying to show the time difference of two timestamps ( finish date , start date ) in Hours:Mins  and also calculate the average of this Hours : Mins by ORDER_NUM .
Please advise.
Thanks again.