title: Linq-to-sql Not Contains or Not in?
body: <p>I'm building a poll widget. I've 2 tables, call them Polls and PollsCompleted. I need to do a linq query to get all the Polls that do not exist for a given user in PollsCompleted.</p>
  
  <p>I have the following sets:</p>
  
  <p>For Polls
  Where Active == True</p>
  
  <p>For PollsCompleted
  Where UserId == ThisUserId
  Where PollId = Polls.Id</p>
  
  <p>Now I need to get all Polls that do not exist in PollsCompleted. I need an example for this using either a single or multiple queries. I've tried to break it down into 2 queries. </p>
  
  <p>Basically, I've 2 IQueryables of type T and T1. I want to take all T's where T.ID does not exist in T1.ParentId.</p>