mysql fetch loop rows delete duplicates without primary keys

Delete_roletouser_Duplicates.sql

DELIMITER ;;

DROP PROCEDURE IF EXISTS Delete_roletouser_Duplicates;;

CREATE PROCEDURE Delete_roletouser_Duplicates()
BEGIN

DECLARE lmt INT DEFAULT 0;
DECLARE done INT DEFAULT 0;
DECLARE _role_id CHAR(36);
DECLARE _user_id CHAR(36);
DECLARE _duplicate_count INT;

DECLARE curRoletouser CURSOR FOR 
  SELECT role_id, user_id, COUNT(*)
  FROM roletouser
  GROUP BY role_id, user_id
  HAVING COUNT(*) > 1;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

OPEN curRoletouser;

getRoletouser: LOOP FETCH curRoletouser INTO _role_id, _user_id, _duplicate_count;
	IF done THEN
		LEAVE getRoletouser;
	END IF;
	SET lmt = _duplicate_count - 1;
	IF lmt > 0 THEN
		DELETE FROM roletouser WHERE role_id = _role_id AND user_id = _user_id LIMIT lmt;
	END IF;
	ITERATE getRoletouser;
END LOOP getRoletouser;

CLOSE curRoletouser;

END;;

DELIMITER ;

CALL Delete_roletouser_Duplicates();