title: is it possible to search for a range on Strings in sqlalchemy
body: <p>I have a table that has HOUSENUM as a String.  Numbers can be 200 or 200A (number with an apt. letter).  I need to filter results from the table using a range of house numbers, ie. 100-450.
  Just to start out I tried:</p>
  
  <pre><code>request=request.filter(table.HOUSENUM.between ('100', '450'))
  </code></pre>
  
  <p>which returns everything.</p>
  
  <p>The letters added to the number make it even more challenging.  Any idea of how I might get all numbers between the range?</p>