Hoe lid te worden van drie tabellen in Codeigniter

Gebruik deze code in model

public function funcname($id)
{
    $this->db->select('*');
    $this->db->from('Album a'); 
    $this->db->join('Category b', 'b.cat_id=a.cat_id', 'left');
    $this->db->join('Soundtrack c', 'c.album_id=a.album_id', 'left');
    $this->db->where('c.album_id',$id);
    $this->db->order_by('c.track_title','asc');         
    $query = $this->db->get(); 
    if($query->num_rows() != 0)
    {
        return $query->result_array();
    }
    else
    {
        return false;
    }
}