title: Regex only allow alphanumeric
body: <p>I am trying to do the following with regex...</p>
  
  <ul>
  <li>Only A-Z and 0-9</li>
  <li>Not one character in its own</li>
  <li>Can not be just numbers on their own</li>
  <li>Can be just letters on their own but at least 2 characters</li>
  </ul>
  
  <p>I have this so far <a href="http://regex101.com/r/zD1jP8" rel="noreferrer">http://regex101.com/r/yW1pV8</a> ...</p>
  
  <pre><code>.*[a-zA-Z]{2,}+.*
  </code></pre>
  
  <p>This seems to meet my critera except that it doesn't stop me from putting in other charactes such as $ _ ! etc...</p>
  
  <p>Some correct test data is...</p>
  
  <pre><code>579 International Road
  International Road
  </code></pre>
  
  <p>Some incorrect data is...</p>
  
  <pre><code>679
  3
  $£
  A
  </code></pre>
  
  <p>Where am I going wrong?</p>