title: Can't set auto-increment via SQL Server Express Management Studio?
body: <p>I just tried inserting value in to a database and that work. Now I insert again and I get an error for identical primary key.</p>
  
  <p>I can't find any option to alter it to be auto-increment.</p>
  
  <p>I'm updating the table via Linq-To-Sql.</p>
  
  <pre><code>User u = new User(email.Text, HttpContext.Current.Request.UserHostAddress,
                                          CalculateMD5Hash(password.Text));
  db.Users.InsertOnSubmit(g);
  db.SubmitChanges();
  </code></pre>
  
  <p>I didn't fill in the <code>user_id</code> and it worked fine the first time. It became zero.
  Trying to add a second user, it wants to make the ID 0 again.</p>
  
  <p>I could query the database and ask for the highest ID, but that's going to far if you know about auto-increment.</p>
  
  <p>How can I turn this on? All I can find are scripts for table creation. I'd like to keep my existing table and simply edit it.</p>