destroy harddisk

Concept

Shredding scheme (an algorithm used for shredding)
-Write Zeros: The simplest method, writes only binary zeros.
- DOD 5220-22.M: More powerful, overwrites data in three passes with random values. This is the default eraser method.
- US Army: Three passes algorithm that complies to the US Army specifications.
- Peter Guttman: Overwrites data in 35 passes. Very slow and in most cases not required.

Download

http://www.harddriveeraser.org/download.php

Reference

http://www.harddriveeraser.org/eraser_help.php

rename table in Oracle

Code

-- for person left outer join title
SELECT p.last_name, t.title_name
FROM person p, title t
WHERE p.title_1 = t.title_abbrev(+);

Reference

http://psoug.org/reference/joins.html

jsp exit page & taglibs table not exist handling

Solution:

To exit page,

Code:

return;

For taglibs, to handle tthe case of table not exist
Code:

<%
boolean is_tableExist = true;
%>


SELECT TOP 1 year
FROM <%= table %>
WHERE [year] > <%= showYear %>
<%= criteria %>
ORDER BY [YEAR] ASC





<%
is_tableExist = false;
%>


<%
if(is_tableExist == false)
{
return;
}
%>

References:
http://jakarta.apache.org/taglibs/doc/dbtags-doc/

rename table or column in MSSQL

Code

1. To rename table,

EXEC sp_rename 'OldTableName', 'NewTableName'

2. To rename column,

EXEC sp_rename
@objname = 'TableName.OldColumnName',
@newname = 'NewColumnName',
@objtype = 'COLUMN'

References

http://yawcerng.blogspot.com/2010/06/ms-sql-rename-table.html

include file in HTML

Code

(replace all "< " to "<")
1. use iframe

< name="content_frame" marginwidth="0" marginheight="0" width="100%" height="30" src="include.html" frameborder="0">< /iframe>

2. use style

< style="border:0px" type="text/x-scriptlet" data="include.html" width="100%" height="30">< /object>

3. work in IIS
file: can use relative path

< !--#include file="include/top_menu.inc" -->
< !--#include file="./include/top_menu.inc" -->

virtual: cannot use ralative path

< !--#include virtual="/tea/include/top_menu.inc" -->

4. work in JSP

< %@include file="include.html"%>

5. work in php

< ?php include("include.html") ?>

References

http://www.boutell.com/newfaq/creating/include.html

Zip files in runtime & output the zip file in .NET

Concept:
1. Open a Package to create a zip file
2. Create a Package Part(URL of the file to add) inside the Package
3. Read the bytes of file to add & add its file stream to the Package
4. Output the zip file with file stream

Code:

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.IO;
using System.IO.Packaging;
using System.Net.Mime;



namespace TEA
{
public partial class WebForm1 : System.Web.UI.Page
{
private const long BUFFER_SIZE = 4096;


protected void Page_Load(object sender, EventArgs e)
{
string zipFileDiectory = "/temp/";
string outputFileName = "download.zip";
string zipFileName = Server.MapPath(zipFileDiectory + outputFileName);


bool is_OK = true;
is_OK &= this.addFileToZip(zipFileName, Server.MapPath("/stafflan/U2810_A4 brochure_AQA Feb2010 v5.pdf"), true);
is_OK &= this.addFileToZip(zipFileName, Server.MapPath("/stafflan/Winter.jpg"), false);

if (is_OK == true)
{
FileStream liveStream = new FileStream(zipFileName, FileMode.Open, FileAccess.Read);
byte[] buffer = new byte[(int)liveStream.Length];
liveStream.Read(buffer, 0, (int)liveStream.Length);
liveStream.Close();

Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Length", buffer.Length.ToString());
Response.AddHeader("Content-Disposition", "attachment; filename=" +
outputFileName);
Response.BinaryWrite(buffer);
}
Response.Write("Compression failed!");
Response.End();
}

private bool addFileToZip(string zipFile, string inputFile, bool is_clearZip)
{
// check if the input file exists
if (File.Exists(inputFile) == false)
{
return false;
}

if(File.Exists(zipFile) == false)
{
Directory.CreateDirectory(Path.GetDirectoryName(zipFile));
}
else if (is_clearZip == true)
{
File.Delete(zipFile);
}
Package package_zip = ZipPackage.Open(zipFile, FileMode.OpenOrCreate, FileAccess.ReadWrite);
string fileInZip = Path.GetFileName(inputFile);
Uri uri_fileInZip = PackUriHelper.CreatePartUri(new Uri(fileInZip, UriKind.Relative));
// if there is existing same name file in the zip, delete it
if(package_zip.PartExists(uri_fileInZip))
{
package_zip.DeletePart(uri_fileInZip);
}
PackagePart packagePart_zip = package_zip.CreatePart(uri_fileInZip, MediaTypeNames.Application.Zip, CompressionOption.Normal);
FileStream fileStream_input = new FileStream(inputFile, FileMode.Open, FileAccess.Read);
Stream stream_output = packagePart_zip.GetStream();
this.copyStream(ref fileStream_input, ref stream_output);
stream_output.Close();
fileStream_input.Close();
package_zip.Close();
return true;
}

private void copyStream(ref FileStream inputStream, ref Stream outputStream)
{
long bufferSize = inputStream.Length < buffer =" new" bytesread =" 0;" byteswritten =" 0;" bytesread =" inputStream.Read(buffer,">


Limitation:
- include automatically "[Content_Types].xml" in the zip file
- cannot create directory inside the zip file
- compression rate is not good
- cannot zip big files larger than Int32

References:
1. http://weblogs.asp.net/jgalloway/archive/2007/10/25/creating-zip-archives-in-net-without-an-external-library-like-sharpziplib.aspx?CommentPosted=true#commentmessage
2. http://www.emoreau.com/Entries/Articles/2008/08/Introducing-SystemIOPackaging.aspx

Solution:

Use DotNetZip Library instead

Code:

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using Ionic.Zip;
using System.IO;


namespace TEA
{
public partial class WebForm1 : System.Web.UI.Page
{
private const long BUFFER_SIZE = 4096;


protected void Page_Load(object sender, EventArgs e)
{
string zipFileDiectory = "/tea/bin/written_brief_file/";
string outputFileName = "download.zip";
string zipFileName = Server.MapPath(zipFileDiectory + outputFileName);

/*
using (ZipFile zipFile = new ZipFile())
{
// add this map file into the "images" directory in the zip archive
zipFile.AddFile(Server.MapPath("/stafflan/U2810_A4 brochure_AQA Feb2010 v5.pdf"), ".");
// add the report into a different directory in the archive
zipFile.AddDirectory(Server.MapPath("/stafflan/FluorineFXTest/"), "FluorineFXTest");
zipFile.Save(zipFileName);
}
*/

// zip all file in a folder
using (ZipFile zipFile = new ZipFile())
{
zipFile.AddDirectory(Server.MapPath("/stafflan"), "");
zipFile.Save(zipFileName);
}


// output files
FileStream liveStream = new FileStream(zipFileName, FileMode.Open, FileAccess.Read);
byte[] buffer = new byte[(int)liveStream.Length];
liveStream.Read(buffer, 0, (int)liveStream.Length);
liveStream.Close();

Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Length", buffer.Length.ToString());
Response.AddHeader("Content-Disposition", "attachment; filename=" +
outputFileName);
Response.BinaryWrite(buffer);
Response.End();

}

}
}

References:
1. http://dotnetzip.codeplex.com/ (API)