title: Checking if the value inserted is a Varchar or an Integer
body: <p>I'm using SQL Developer/Oracle and I need to check in a trigger if the the value inserted on a specific field is an integer or just a "string".</p>
  
  <p>I tried <code>isnumeric()</code>, but this function doesn't exist in Oracle. What's the equivalent in Oracle since I can't find it anywhere?</p>