Oracle 5.0 Reference Manual page 1934

The method of the
Read
according to the
After assigning the byte array as a parameter of the
method is called and the
20.2.5.10.3. Reading a BLOB from the Database to a File on Disk
Once a file is loaded into the
The following code retrieves a row from the
to be written to disk:
Visual Basic Example
Dim conn As New MySqlConnection
Dim cmd As New MySqlCommand
Dim myData As MySqlDataReader
Dim SQL As String
Dim rawData() As Byte
Dim FileSize As UInt32
Dim fs As FileStream
conn.ConnectionString = "server=127.0.0.1;" _
& "uid=root;" _
& "pwd=12345;" _
& "database=test"
SQL = "SELECT file_name, file_size, file FROM file"
Try
conn.Open()
cmd.Connection = conn
cmd.CommandText = SQL
myData = cmd.ExecuteReader
If Not myData.HasRows Then Throw New Exception("There are no BLOBs to save")
myData.Read()
FileSize = myData.GetUInt32(myData.GetOrdinal("file_size"))
rawData = New Byte(FileSize) {}
myData.GetBytes(myData.GetOrdinal("file"), 0, rawData, 0, FileSize)
fs = New FileStream("C:\newfile.png", FileMode.OpenOrCreate, FileAccess.Write)
fs.Write(rawData, 0, FileSize)
fs.Close()
MessageBox.Show("File successfully written to disk!", "Success!", MessageBoxButtons.OK, MessageBoxIcon.
myData.Close()
conn.Close()
Catch ex As Exception
MessageBox.Show("There was an error: " & ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Erro
End Try
C# Example
MySql.Data.MySqlClient.MySqlConnection conn;
MySql.Data.MySqlClient.MySqlCommand cmd;
MySql.Data.MySqlClient.MySqlDataReader myData;
conn = new MySql.Data.MySqlClient.MySqlConnection();
cmd = new MySql.Data.MySqlClient.MySqlCommand();
string SQL;
UInt32 FileSize;
Connector/Net Programming
object is used to load the file into a byte array which is sized
FileStream
property of the
Length FileStream
is inserted into the
BLOB
table, we can use the
file
object.
object, the
MySqlCommand
table.
file
MySqlDataReader
table, then loads the data into a
file
1914
ExecuteNonQuery
class to retrieve it.
object
FileStream