Sql to get average timestamp between 2 timestamps

Question

I know similar question has been asked many times in several forums. Most of them dealt with fetching interval or difference between timestamps in numbers (hours, mins,...) or using PL/SQL or custom functions.
Without using PL or custom functions, but just a sql what's the most efficient way of calculating timestamp that's half way between 2 timestamps?
alter session set nls_date_format = 'YYYY-MM-DD HH24:MI:SS';
select
to_date('2013-12-05 04:30:20','YYYY-MM-DD HH24:MI:SS') start_date,
to_date('2013-12-06 15:00:30','YYYY-MM-DD HH24:MI:SS') end_date,
'' avg_date
from dual;
Thanks,
-srinivas y.

Answer 1

Hi,
Here's one way to get the mid-point between 2 DATEs:
WITH  input_data  AS
    SELECT  TO_DATE ('2013-12-05 04:30:20', 'YYYY-MM-DD HH24:MI:SS')   AS start_date
    ,       TO_DATE ('2013-12-06 15:00:30', 'YYYY-MM-DD HH24:MI:SS')   AS end_date
    FROM     dual
SELECT  start_date, end_date
,       start_date + ( (end_date - start_date)
                     / 2
                     )    AS mid_point
FROM    input_data
If start_date and end_date are already in a table, then use that table instead of a sub-query like input_data above.
Message was edited by: Frank Kulash
Actually, this works equally well if start_date and end_date are TIMESTAMPs.
(TIMESTAMP is a separtate datatype from DATE.  You asked about TIMESTAMPs, but the example you gave used DATEs.  If you really want TIMESTAMPs, you can use TO_TIMESTAMP instead of TO_DATE.)