1）Setting up HTML form for file uploading.
<form id="Form1" method="post" runat="server" enctype="multipart/form-data">
<input id="filMyFile" type="file" runat="server">

2）Receiving uploaded file.
protected HtmlInputFile filMyFile;
if( filMyFile.PostedFile != null )
{
// File was sent
}
else
{
// No file
}
// Get a reference to PostedFile object
HttpPostedFile myFile = filMyFile.PostedFile;

// Get size of uploaded file
int nFileLen = myFile.ContentLength;
// Allocate a buffer for reading of the file
byte[] myData = new byte[nFileLen];
// Read uploaded file from the Stream
myFile.InputStream.Read(myData, 0, nFileLen);

3）Saving uploaded file to disk
// Writes file to current folder
private void WriteToFile(string strPath, ref byte[] Buffer)
{
// Create a file
FileStream newFile = new FileStream(strPath, FileMode.Create);

// Write data to the file
newFile.Write(Buffer, 0, Buffer.Length);

// Close file
newFile.Close();
}
string strFilename = Path.GetFileName(myFile.FileName);
4）Saving uploaded file to database
<PRE id=pre9 style="MARGIN-TOP: 0px" nd="42">// Writes file to the database
private int WriteToDB(string strName, string strType, ref byte[] Buffer)
{
int nFileID = 0;

// Create connection
OleDbConnection dbConn = new OleDbConnection(GetConnectionString());

// Create Adapter
OleDbDataAdapter dbAdapt = new OleDbDataAdapter("SELECT * FROM tblFile", dbConn);

// We need this to get an ID back from the database
dbAdapt.MissingSchemaAction = MissingSchemaAction.AddWithKey;

// Create and initialize CommandBuilder
OleDbCommandBuilder dbCB = new OleDbCommandBuilder(dbAdapt);

// Open Connection
dbConn.Open();

// New DataSet
DataSet dbSet = new DataSet();

// Populate DataSet with data
dbAdapt.Fill(dbSet, "tblFile");

// Get reference to our table
DataTable dbTable = dbSet.Tables["tblFile"];

// Create new row
DataRow dbRow = dbTable.NewRow();

// Store data in the row
dbRow["FileName"] = strName;
dbRow["FileSize"] = Buffer.Length;
dbRow["ContentType"] = strType;
dbRow["FileData"] = Buffer;

// Add row back to table
dbTable.Rows.Add(dbRow);

// Update data source
dbAdapt.Update(dbSet, "tblFile");

// Get newFileID
if( !dbRow.IsNull("FileID") )
nFileID = (int)dbRow["FileID"];

// Close connection
dbConn.Close();

// Return FileID
return nFileID;
}
</PRE>

5）Retrieving of a file from database.
<PRE nd="59">private void Page_Load(object sender, System.EventArgs e)
{
// Check if FileID was passed to this page as a parameter
if( Request.QueryString["FileID"] != null )
{
// Get the file out of database and return it to requesting client
ShowTheFile(Convert.ToInt32(Request.QueryString["FileID"]));
}

}
</PRE>
<PRE id=pre11 style="MARGIN-TOP: 0px" nd="62">// Read file out of the database and returns it to client
private void ShowTheFile(int FileID)
{
// Define SQL select statement
string SQL = "SELECT FileSize, FileData, ContentType FROM tblFile WHERE FileID = "
+ FileID.ToString();

// Create Connection object
OleDbConnection dbConn = new OleDbConnection(GetConnectionString());

// Create Command Object
OleDbCommand dbComm = new OleDbCommand(SQL, dbConn);

// Open Connection
dbConn.Open();

// Execute command and receive DataReader
OleDbDataReader dbRead = dbComm.ExecuteReader();

// Read row
dbRead.Read();

// Clear Response buffer
Response.Clear();

// Set ContentType to the ContentType of our file
Response.ContentType = (string)dbRead["ContentType"];

// Write data out of database into Output Stream
Response.OutputStream.Write((byte[])dbRead["FileData"], 0, (int)dbRead["FileSize"]);

// Close database connection
dbConn.Close();

// End the page
Response.End();
}
</PRE>