把从SQL中取出的数据转化成XMl格式

    }

    /**
    * Adds the content of a xml-file to $this->xmldoc, on the same level
    * as a normal resultset (mostly just below <root>)
    *
    * @param    string filename
    * @param    mixed xpath  either a string with the xpath expression or an array with "xpath"=>xpath expression  and "root"=tag/subtag/etc, which are the tags to be inserted before the result
    * @access   public
    * @see      doXmlString2Xml()
    */

    function addXmlFile($file,$xpath = Null)
    {
        $fd = fopen( $file, "r" );
        $content = fread( $fd, filesize( $file ) );
        fclose( $fd );
        $this->doXmlString2Xml($content,$xpath);
    }

    /**
    * Adds the content of a xml-string to $this->xmldoc, on the same level
    * as a normal resultset (mostly just below <root>)
    *
    * @param    string xml
    * @param    mixed xpath  either a string with the xpath expression or an array with "xpath"=>xpath expression  and "root"=tag/subtag/etc, which are the tags to be inserted before the result
    * @access   public
    * @see      doXmlString2Xml()
    */