title: EF: Inserting already present record in many to many relationship
body: <p>For what I searched there are 2 ways to insert an already present record into a ICollection list:</p>
  
  <ol>
  <li><code>group.Users.Add(db.Users.FirstOrDefault(x=&gt; x.Id = 1));</code></li>
  <li><code>var to_add = new User{Id: 1}; db.Users.Attach(to_add); group.Users.Add(to_add);</code></li>
  </ol>
  
  <p>The problem with both the above approach is it makes a db call every time we want to add a record. While we already know the user's Id and the group's id and that's all it needs to create a relationship.</p>
  
  <p>Imagine a long list to be added, both the above methods would make multiple calls to db.</p>