La conversion de blob à l'origine du type de fichier et le rendre disponible pour le téléchargement

utiliser cet exemple et modifier la base de données SQL de votre Base de données ainsi que l'Instruction Select

SqlConnection pubsConn = new SqlConnection("Data Source=localhost;Integrated Security=SSPI;Initial Catalog=pubs;");
SqlCommand logoCMD = new SqlCommand("SELECT pub_id, logo FROM pub_info", pubsConn);
FileStream fs;                          //Writes the BLOB to a file (*.bmp).
BinaryWriter bw;                        //Streams the BLOB to the FileStream object.
int bufferSize = 100;                   //Size of the BLOB buffer.
byte[] outbyte = new byte[bufferSize];  //The BLOB byte[] buffer to be filled by GetBytes.
long retval;                            //The bytes returned from GetBytes.
long startIndex = 0;                    //The starting position in the BLOB output.
string pub_id = "";                     //The publisher id to use in the file name.
//Open the connection and read data into the DataReader.
pubsConn.Open();
SqlDataReader myReader = logoCMD.ExecuteReader(CommandBehavior.SequentialAccess);
while (myReader.Read())
{
//Get the publisher id, which must occur before getting the logo.
pub_id = myReader.GetString(0);  
//Create a file to hold the output.
fs = new FileStream("logo" + pub_id + ".bmp", FileMode.OpenOrCreate, FileAccess.Write);
bw = new BinaryWriter(fs);
//Reset the starting byte for the new BLOB.
startIndex = 0;
//Read the bytes into outbyte[] and retain the number of bytes returned.
retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize);
//Continue reading and writing while there are bytes beyond the size of the buffer.
while (retval == bufferSize)
{
bw.Write(outbyte);
bw.Flush();
//Reposition the start index to the end of the last buffer and fill the buffer.
startIndex += bufferSize;
retval = myReader.GetBytes(1, startIndex, outbyte, 0, bufferSize);
}
//Write the remaining buffer.
bw.Write(outbyte, 0, (int)retval - 1);
bw.Flush();
//Close the output file.
bw.Close();
fs.Close();
}
//Close the reader and the connection.
myReader.Close();
pubsConn.Close();

OriginalL'auteur MethodMan