title: Is there a difference if I don't define a Primary Key in a table
body: <p>I've been using SQL Server for quite a while, I always create database with design view.</p>
  
  <p>The steps I took to create the table is:</p>
  
  <ul>
  <li>Right Click Table -> New Table </li>
  <li>I always have the first column as <code>SOMETHING_ID</code> (int) -> I make <code>SOMETHING_ID</code> as <code>Identity</code> with auto increment of 1 </li>
  <li>-> Then I add other columns </li>
  <li>-> Save and use</li>
  </ul>
  
  <p>As you can see, I didn't define <code>SOMETHING_ID</code> by right clicking it and SET AS PRIMARY.</p>
  
  <p>Will there be any performance impact in this case?</p>