Authentication by email and group/access level

[eluser]doubleplusgood[/eluser]
Hi there,
I have built and admin controller and would like the is_valid_user function to check the email address and also check that that user has a particular group/access level.

My login and is_valid_user functions are as follows;

Code:

function login()
{
    $email = $this->input->post('email');
    $password = $this->input->post('password');
    
    if ( empty($email) || empty($password) )
    {
        die('fill it in!');
    }
    
    $logged_in = $this->auth->login($email, $password);
    
    redirect('admin');
}

function is_valid_user($email)
{    
    $this->db->where('email', $email);
    $query = $this->db->get('users', 1);
    
    if ( $query->num_rows() == 1 )
    {
        return TRUE;
    }
    else
    {
        $this->form_validation->set_message('is_valid_user', 'This user is not registered!');
        
        return FALSE;
    }
}

I attempted the following query to check the email and groupid (access level);

Code:

$sql = "SELECT * FROM users WHERE email = ? AND groupid = ?";
$this->db->query($sql, array($email,5));
            
$query = $this->db->get('users', 1);

I wondered if anyone had any ideas on how to get this working? Thank you.