title: MySQL-Masking credit card numbers but keeping the hyphens
body: <p>I need to return a column of credit card numbers from DB table 'orders' column is 'card_number'. They are in this format on the 'orders' table:</p>
  
  <blockquote>
    <p>1234-5678-9012-3456</p>
  </blockquote>
  
  <p>I need the SELECT statement to return with this:</p>
  
  <blockquote>
    <p>xxxx-xxxx-xxxx-3456</p>
  </blockquote>
  
  <p>I've found examples without hyphens and adding hyphens where there are none showing this. I'm stumped.</p>