title: How to check if a list of ids exists in db without fetching the count and compare it to the list count
body: <p>I know this sounds like a duplicate question, but what I want is slightly different from other answers.
  Technically I want to get this query sent to the database using Linq:</p>
  
  <pre><code>Select Count(*) = 3 From Products Where Id in (1,2,3)
  </code></pre>
  
  <p>Notice this query returns True if all ids exist, and False if any of them doesn't.
  It is kind of <code>Products.Exists(p =&gt; ids.Contain(p.Id))</code> but all the ids should exists.</p>