private function queryFirstDate($assetTypeCode)
    {
        $query = $this->qbGetFirstDate->build();
        $bind = [
            $this->qbGetFirstDate::BND_ASSET_TYPE_CODE => $assetTypeCode
        ];
        $conn = $query->getConnection();
        $result = $conn->fetchOne($query, $bind);
        return $result;
    }