title: Entity framework does not return null
body: <p>I'm getting a bit confused here. If my query does not return anything why isnt coupon null? And how should I check for null?</p>
  
  <pre><code>Coupon coupon;
  
  using (var db = new KupongEntities())
  {
      coupon = (from p in db.Coupon
          where p.CouponID == 123
          select p).SingleOrDefault();
  }
  
  if (coupon != null)
  {
      //test
  }
  </code></pre>