Current Hour -5

Question

Hello I am building a subselect to display the current date, month and HOUR-4 in the format DDMM(HH-4) e.g Current date: 17 Sep 10am -> Needed Select output 170906
I have tried the following and it is quite close:
SELECT TO_CHAR(SYSDATE, 'DD')||
TO_CHAR(SYSDATE, 'MM')||
DECODE ((TO_CHAR(SYSDATE, 'HH24')),
-4, 00,
-3, 01,
-2, 02,
-1, 03,
(TO_CHAR(SYSDATE, 'HH24')-04))
FROM DUAL;
Unfortunatelly it truncates the 0 from the hour and i need the hour in HH24 format
170906 ->needed
17096 -> what I get.
Any help will be much appreciated.
Thank you

Answer 1

look at your code, the output is correct:
SQL> select to_char(sysdate, 'hh24') from dual;
TO
09
SQL>
but as you now subtract 4 from the result, Oracle has to convert the string to a number and the default number format is without leading 0.
You could format it again with a to_char(..., '09')
But why don't you just let Oracle do the math in the date?
SQL> select sysdate, to_char(sysdate - 4/24, 'hh24') from dual;
SYSDATE             TO
17.09.2010 09:43:06 05
SQL>