@RidIculous . :
$user = $this->db->escape($user);
$this->db->select('id,level,email,username');
$this->db->where("(email = $user OR username = $user)");
$this->db->where('password', $pass);
$query = $this->db->get('users');
, (PHP 5 +)
$user = $this->db->escape($user);
$query = $this->db
->select('id,level,email,username')
->where("(email = $user OR username = $user)")
->where('password', $pass)
->get('users');