protected function insertDefault( $table, $rows ) {

        $columns = $this->getColumns( $rows );
        if ( empty( $columns ) ) return;

        $query = $this->insertHead( $table, $columns );
        $lists = $this->valueLists( $rows, $columns );

        foreach ( $lists as $list ) {

            $singleQuery = $query . $list;

            $this->onQuery( $singleQuery );

            $statement = $this->prepare( $singleQuery );
            $statement->execute();

        }

        return $statement; // last statement is returned

    }