Problem returning max date in 2009

Question

Is anyone else experiencing this problem?
Create the following table and add the data....
CREATE TABLE ETL_LASTRUN
LAST_RUN DATE
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('12/31/2008 23:17:13', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('12/31/2008 23:26:31', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('12/31/2008 23:36:35', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('12/31/2008 23:46:23', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('12/31/2008 23:56:30', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('01/01/2009 00:06:36', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('01/01/2009 00:16:39', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('01/01/2009 00:26:30', 'MM/DD/YYYY HH24:MI:SS'));
Insert into ETL_LASTRUN
(LAST_RUN)
Values
(TO_DATE('01/01/2009 00:36:38', 'MM/DD/YYYY HH24:MI:SS'));
COMMIT;
Now, run the following query
SELECT MAX(to_char(last_run,'MM/DD/YYYY HH24:MI')) as last_run FROM etl_lastrun
The results I get (using 10.2.0.1.0)
last_run
=====
12/31/2008 23:56

Answer 1

SQL> SELECT MAX(to_char(last_run,'MM/DD/YYYY HH24:MI')) as last_run FROM etl_lastrun
  2  /
LAST_RUN
12/31/2008 23:56
1 rij is geselecteerd.I get the same expected result. Expected, because you are taking the max of the character representation of the date. And '12/31...' is greater than '01/01...'. You can see that like this:
SQL> select to_char(last_run,'MM/DD/YYYY HH24:MI')
  2    from etl_lastrun
  3   order by 1
  4  /
TO_CHAR(LAST_RUN
01/01/2009 00:06
01/01/2009 00:16
01/01/2009 00:26
01/01/2009 00:36
12/31/2008 23:17
12/31/2008 23:26
12/31/2008 23:36
12/31/2008 23:46
12/31/2008 23:56
9 rijen zijn geselecteerd.So switch the max function and the to_char display function for the desired result:
SQL> select to_char(max(last_run),'MM/DD/YYYY HH24:MI') as last_run
  2    from etl_lastrun
  3  /
LAST_RUN
01/01/2009 00:36
1 rij is geselecteerd.Regards,
Rob.