public function donovan( QuoteInterface $quoting, $prefix, $columns )
    {
        $sql = array();
        foreach( $columns as $column => $type ) {
            $sql[] = sprintf(
                'donovan(%s%s)',
                $prefix,
                $quoting->quoteIdent( $column )
            );
        }
        return sprintf(
            "'['||%s||']'",
            implode("||','||", $sql)
        );
    }