title: How to specify Ruby regex when using Active Record in Rails?
body: <p>To get all jobs which <code>invoice_number</code> is a pure number I do:</p>
  
  <pre><code>Job.where("invoice_number REGEXP '^[[:digit:]]+$'")
  </code></pre>
  
  <p>Is it possible to do the same by specifying the regex in Ruby rather than MySQL ?</p>