How to subtract hours from a date in Oracle so it affects the day also

Question

I\'m trying to subtract date from Oracle so it even effect the day as well. For example, if the timestamp is 01/June/2015 00 hours and if I subtract 2 hours, I want to be able

Answer 1

you should divide hours by 24 not 11
like this:
select to_char(sysdate - 2/24, 'dd-mon-yyyy HH24') from dual