title: joining two tables in entity framework
body: <p>i'm trying to join two tables in entity framework and get the value from one of them to do another query on a third table 
  this is the query i'm using </p>
  
  <pre><code>  var fav = from favs in db.FAVORITES
  
                        join pins in db.PINS
                        on new { favs.USER_ID, favs.PIN_ID } equals new { userId, pins.PIN_ID } into res
                        from r in res
                        select new { favs.PIN_ID, r.TYPE_ID };
  </code></pre>
  
  <p>but it gives me a syntax error in 
  <strong>The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'GroupJoin'</strong>
  i have searched about the error and find that the people always say to make sure that the properties in the <strong>equals</strong> clause are the same type, and yes the are all of type non nullable int </p>