Undefined property: CI_Loader::$db

[eluser]vickel[/eluser]
I'm new to CI and stuck when trying to connect to mySQL database

my code is like suggested in the userguide:

<?php
$this->load->database();
//$this->db->query('SELECT username FROM users');
$query = $this->db->query('SELECT username FROM users');

foreach ($query->result_array() as $row)
{
echo $row['username'];
echo "<br>...<br />";
}
?&gt;

unfortunately I get this error:

A PHP Error was encountered
Severity: Notice
Message: Undefined property: CI_Loader::$db
Filename: views/dbteste.php
Line Number: 12

if anyone could explain me this, I'd apreciate immensly, thanks