title: Datediff sql query to linq lambda query
body: <p>How do I translate this SQL function to linq query lambda expression?</p>
  
  <pre><code>SELECT Type, DATEDIFF(day,Expiry_Date,GETDATE()) AS Days
  FROM Item
  GROUP BY Type, Expiry_Date;
  </code></pre>
  
  <p>Do I first need to create a function in my database?</p>