title: SQL JOIN doesn't find guests, only users
body: <p>I am using this line of SQL code:</p>
  
  <pre><code>SELECT DISTINCT tb_online.ip, tb_users.id, tb_online.login, tb_online.page 
  FROM tb_online
  JOIN tb_users 
    ON tb_online.login=tb_users.username 
  ORDER BY login ASC
  </code></pre>
  
  <p>The problem is that this line <code>ON tb_online.login=tb_users.username</code> means that SQL query only selects users but not guests (<em>they don't have username in the <code>tb_users</code> table</em>).</p>
  
  <p>How could I make SQL query to <strong>select both users and guests</strong>?</p>