Mysql UPDATE bez overwrite-a Pomoc

Programiranje
1

Pozz
Imam 1 problem, radim na jednom CMS-u gdje mi treba da radi update 1 fielda ali da ne obrise stari unos nego doda samo novi u taj field.

public function join_ladder($id, $username, $team_id)
{
	$query = $this->db->prepare("UPDATE team SET ladder_id = ? WHERE team_creator = ? AND team_id = ?");
	$query->bindValue(1, $id);
	$query->bindValue(2, $username);
	$query->bindValue(3, $team_id);
	$query->execute();
}
2