title: Oracle trim whitespace on the inside of a string
body: <p>I am storing phone numbers as VARCHAR2 in my system to allow for users to input '+' characters infront of their phone number if they so choose.</p>
  
  <p>My regexp allows for this perfectly, but when storing the number in the database I want to strip out all whitespace the user may enter.  </p>
  
  <p>My regexp allows for the following formats </p>
  
  <pre><code>+4470123456789
  +447 0123456789
  +447 01234 56789
  01234567890
  01234 567890
  01234 567 890
  </code></pre>
  
  <p>I know I could resolve my issue by not letting users put any whitespace in their numbers, but I know from personal experience just how frustrating it is to have a validation error due to some silly formatting on the client side.  I have tried using the TRIM function on my INSERT/UPDATE trigger but I have realised that is limited to only front and trailing whitespace, is there any other function in Oracle I could use that would remove internal whitespace? Or do I need to write my own function to do this?</p>
  
  <p>Any pointers would be greatly appreciated.</p>