title: How to write this SQL query in Linq To SQL
body: <p>I would like to know how to write the following SQL query in Linq. I've tried but without luck.</p>
  
  <pre><code>/*Variable*/
  topicId = '4a31c2ee-48af-4b87-b300-112acb822ad0'
  
  select * from Contents c
  left join ContentToTopicRelations ctr on ctr.ContentId = c.ContentId and ctr.TopicId = topidId
  where ctr.ContentId is null
  </code></pre>
  
  <p>Basically, I would like to get all the contents that are not in ContentToTopicRelations table <strong>for a particular topicId</strong>.</p>