Mysql Query ze zmienną mysql nie działa w Zend Framework 1

Konfiguracja Zend to: resources.db.adapter = "pdo_mysql"

zapytanie, które dostajeKomunikat: SQLSTATE [HY000]: Błąd ogólny

$db = Zend_Db_Table::getDefaultAdapter();
        $db->setFetchMode(Zend_Db::FETCH_ASSOC);       


        $qry =  $db->fetchAll(" SET @rank = 0 ;
                                SELECT
                                   @rank := @rank +1 AS rank,
                                    SUM(user_scoring_data.user_points)  AS user_points,
                                    league_team.user_id

                                FROM league_team 
                                RIGHT JOIN user_scoring_data ON league_team.league_team_id = user_scoring_data.league_team_id

                                WHERE league_id = '$league_id' GROUP BY user_scoring_data.league_team_id 
                                ORDER BY user_points DESC"
                            );

jeśli usunę zmienną mysql, działa:

$db->fetchAll("
                                SELECT
                                    SUM(user_scoring_data.user_points)  AS user_points,
                                    league_team.user_id

                                FROM league_team 
                                RIGHT JOIN user_scoring_data ON league_team.league_team_id = user_scoring_data.league_team_id

                                WHERE league_id = '$league_id' GROUP BY user_scoring_data.league_team_id 
                                ORDER BY user_points DESC"
                            );

* Uwaga: zapytanie zostało przetestowane bezpośrednio w phpmyadmin i nie zawiera błędów.

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