Calculating Date Difference

Question

Hello,
I am trying to calculate the difference between dates. I have a date_received column and a date_compleated column in my table with data type "date". The values are strings originally, and are converted and stored in the database using to_date. For instance: to_date(:DATE_REC,'DD-Mon-YY HH:MI:SS AM'). When I query the database, I get a negative number for difference.
Query
SELECT to_char(date_compleated, 'DD-MON-YY HH:MI:SS AM') date_comp,
to_char(date_received, 'DD-MON-YY HH:MI:SS AM') date_rec,(date_compleated - date_received) Diff
FROM cs_request
where job_number = '23089791';
Results
DATE_COMPL
10-JUL-08 03:09:43 PM
DATE_REC
09-JUL-08 08:09:08 AM
DIFF
-730485.70792824074074074074074074074074
Why am I getting a negative number? Any suggestions would be greatly appreciated.
Sharon

Answer 1

Quite possibly that DATE_COMPLEATED value got converted to :
'10-JUL-0008 03:09:43 PM'
instead of:
'10-JUL-2008 03:09:43 PM'
test@ora>
test@ora>
test@ora> --
test@ora> with t as (
  2    select to_date('10-JUL-0008 03:09:43 PM','DD-MON-YYYY HH:MI:SS AM') as date_compleated,
  3           to_date('09-JUL-2008 08:09:08 PM','DD-MON-YYYY HH:MI:SS AM') as date_received
  4    from dual)
  5  --
  6  SELECT
  7    to_char(date_compleated, 'DD-MON-YY HH:MI:SS AM') date_comp,
  8    to_char(date_received, 'DD-MON-YY HH:MI:SS AM') date_rec,
  9    (date_compleated - date_received) Diff
10  FROM t;
DATE_COMP             DATE_REC                    DIFF
10-JUL-08 03:09:43 PM 09-JUL-08 08:09:08 PM -730486.21
1 row selected.
test@ora>
test@ora>
test@ora>
test@ora>What is the output of this query ?
SELECT to_char(date_compleated, 'DD-MON-YYYY HH:MI:SS AM') date_comp
FROM   cs_request
where  job_number = '23089791'; HTH
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