Select query with else

Hello,
I have a few questions and hope you can help me there.
In my old version I made such a query.

PHP Code:

           $sql = "SELECT
                        tb_kunde_id
                    FROM
                        db_kunde
                    WHERE
                        tb_kunde_vorname = :vorname
                            AND
                                tb_kunde_nachname = :nachname
                            AND
                                tb_kunde_land = :land";
            $select = $db->prepare($sql);
            $select->bindParam(':vorname', $tb_kunde_vorname);
            $select->bindParam(':nachname', $tb_kunde_nachname);
            $select->execute();
            if($select->rowCount() < 1)
                {
                    $client_data['tb_kunde_vorname'] = $tb_kunde_vorname;
                    $client_data['tb_kunde_nachname'] = $tb_kunde_nachname;
                    $add_client = $db->insert("db_kunde",$client_data) OR die("Error: ".$db->error()."</br> Zeile ".__LINE__);
                    $id_kunde = $db->lastInsertId();
                }
            else
                {
                    $results = $select->fetch(PDO::FETCH_NUM);
                    $id_kunde = $results[0];
                } 


Now I wonder how I need to query this in ELSE?

In CodeIgniter Query Builder style:

PHP Code:

$this->db
->select('tb_kunde_id')
->from('db_kunde')
->where('tb_kunde_vorname',$tb_kunde_vorname)
->where('tb_kunde_nachname', $tb_kunde_nachname)
->where('tb_kunde_land', $tb_kunde_land);

$query = $this->db->get();

if ($query->num_rows() == 0) {
  $this->db->insert('db_kunde',$client_data);
  $id_kunde = $this->db->insert_id();
}
else {
  $id_kunde = $query->row()->tb_kunde_id;
} 


thanks