protected static $users = array(
  'us1' => array('password'=>"pass1", 'fullname'=>"name1", 'email'=>"name1@mail.com"),
  'us2' => array('password'=>"pass2", 'fullname'=>"name2", 'email'=>"name2@mail.com"),
  'us3' => array('password'=>"pass3", 'fullname'=>"name3", 'email'=>"name3@mail.com"),
);

$sql = mysql_query('select username, password, fullname, email FROM s_users');
$users = array()

while ($row_user = mysql_fetch_assoc($sql))
  $users[] = $row_user;

while ($row_user = mysql_fetch_assoc($sql)) {
  $users[$row_user['username']] = $row_user;
}