public function getJoinRS() {
        $join = "SELECT * FROM (SELECT m.ID AS MID, m.UserID, m.GroupID, m.Name, m.SName, " .
                "m.Mail, g.ID AS GID, g.Name AS GName, g.IsSystem FROM " .
                "`RS_MailList` AS m JOIN RS_Groups AS g ON m.UserID = g.UserID) as j " .
                "GROUP BY Mail";
        try {
            $result = $this->_rs->query($join)->fetchAll(PDO::FETCH_ASSOC);
            return $result;
        } catch (PDOException $ex) {
            echo "Error function getJoinRS(): " . $ex->getMessage() . "\n";
            return false;
        }
    }

public function items() {
        $rs = $this->getJoinRS();
        foreach($rs as $mail) {
            $sql = "SELECT * FROM (SELECT m.ID AS MID, m.UserID, m.GroupID, m.Name, m.SName, " .
                    "m.Mail, g.ID AS GID, g.Name AS GName, g.IsSystem FROM " .
                    "`RS_MailList` AS m JOIN RS_Groups AS g ON m.UserID = g.UserID) as j " .
                    "WHERE Mail='" .$mail['Mail'] . "' GROUP BY UserID";
            $rs_result = $this->_rs->query($sql)->fetchAll(PDO::FETCH_ASSOC);
            foreach ($rs_result as $alter) {
        $query = "SELECT id FROM `MailData` WHERE eMail = '" . $mail['Mail'] . "'";
                $rid = $this->_alter->query($query)->fetchAll(PDO::FETCH_ASSOC);
                $id = (int) $rid[0]['id'];
        $i = 0;
                $this->_alter->beginTransaction();
                echo "Transaction for mail address " . $mail['Mail'] . " of UserID " . $alter['UserID'] . " prepare...\n";
                $t = $this->_alter->prepare("INSERT INTO `SubscriberData` (FirstName, LastName) VALUES (:fname, :lname)");
                $t->bindParam(':fname', $alter['Name'], PDO::PARAM_STR);
                $t->bindParam(':lname', $alter['SName'], PDO::PARAM_STR);
                $t->execute();
                $i++;
                $subscriberID = $this->_alter->lastInsertId();
                $item = $this->_alter->prepare("INSERT INTO `ListItem` (UserID, SubscriberID, MailID, ConfirmHash) VALUES (:userID, :subID, :mailID, :hash)");
                $hash = md5($alter['Mail']);
                $item->bindParam(':userID', $alter['UserID'], PDO::PARAM_INT);
                $item->bindParam(':subID', $subscriberID, PDO::PARAM_INT);
                $item->bindParam(':mailID', $id, PDO::PARAM_INT);
                $item->bindParam(':hash', $hash, PDO::PARAM_STR);
                $item->execute();
                $i++;
                $listItemID = $this->_alter->lastInsertID();
                $sql2 = "SELECT * FROM (SELECT m.ID AS MID, m.UserID, m.GroupID, m.Name, m.SName, " .
                        "m.Mail, g.ID AS GID, g.Name AS GName, g.IsSystem FROM " .
                        "`RS_MailList` AS m JOIN RS_Groups AS g ON m.UserID = g.UserID) as j " .
                        "WHERE MID='" . (int) $alter['MID'] . "' GROUP BY UserID, GID";
                $rs_group = $this->_rs->query($sql2)->fetchAll(PDO::FETCH_ASSOC);
                foreach ($rs_group as $g) {
                    $group = $this->_alter->prepare("INSERT INTO `Tags` (nameTag, UserID) VALUES (:name, :userID)");
                    $group->bindParam(':name', $g['GName'], PDO::PARAM_STR);
                    $group->bindParam(':userID', $g['UserID'], PDO::PARAM_INT);
                    $group->execute();
                    $i++;
                    $groupID = $this->_alter->lastInsertId();
                    $tags = $this->_alter->prepare("INSERT INTO `TagsListItem` (ItemID, TagID) VALUES (:item, :tag)");
                    $tags->bindParam(':item', $listItemID, PDO::PARAM_INT);
                    $tags->bindParam(':tag', $groupID, PDO::PARAM_INT);
                    $tags->execute();
                    $i++;
                }
                try {
                    echo "Transaction for mail address ". $mail['Mail'] . " of UserID " . $alter['UserID'] . " start. All queries: " .$i. "\n";
                    $this->_alter->commit();
                    echo "Transaction complete\n";
                } catch (PDOException $ex) {
                    $this->_alter->rollBack();
                    echo "Transaction error: " . $ex->getMessage() . "\n";
                }
            }
        }
    }
}