title: How can I find which elements *in* my set do not match?
body: <pre><code>SELECT
  *
  FROM
  users
  WHERE
  username IN ("john", "bob", "ray", "sexay")
  </code></pre>
  
  <p>Let's say I have these in my table:</p>
  
  <pre><code>ID  USERNAME
  ------------------
  1   john
  2   bob
  3   jack
  </code></pre>
  
  <p>I want to know which of my set did not match, so I need <code>"ray" and "sexay"</code>. Is there a pure SQL way of doing this? I know I can do this with multiple queries but I have 200 or so users and if it's possible to do it in one query then great.</p>
  
  <p>EDIT #1: A pure <code>NOT IN</code> is not sufficient because that would return all users that do not match my username set. I don't need every single one, just every single username string in my given set that doesn't match.</p>