title: Include null in oracle regex
body: <p>I've been trying the following but it does not return any (null) values. How can I include null values in using a regular expression with oracle an in fact return everything including null. (It is necessary to use a regex as the value is replaced with a variable in python and so the value will not always be null. Otherwise i could just leave out the expression.)</p>
  
  <pre><code>SELECT * from table WHERE
  REGEXP_LIKE (column1,'.*|NULL$')
  </code></pre>