title: How to subtract hours from a date in Oracle so it affects the day also
body: <p>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 to go to to 31/May/2014 22 hours. </p>
  
  <p>I tried</p>
  
  <pre><code>to_char(sysdate-(2/11), 'MM-DD-YYYY HH24')
  </code></pre>
  
  <p>but it only subtracts the hour; it does not touch the day itself.</p>