How to retrieve images from MySQL database and display as a slide show in Windows Forms application using C# and VB.NET

By | November 29, 2012

In this article I will explain how to retrieve images stored in BLOB field of MySQL database and display as a slide show in Windows Forms application using C#

Download source code


In previous article I explained how to save images in Windows Forms application using C#. In this article I will explain how to retrieve images from MySQL database using SequentialAccess and show as a slide show in a Windows Forms application


Insert some images in the database as discussed in the previous article. Add a new Form to the Windows Application and add a PictureBox, a Button and a BackgroundWorker control to the Form

Write following in Load event of the Form

C# code:

private void Form2_Load(object sender, EventArgs e)
    ConString = System.Configuration.ConfigurationManager.ConnectionStrings["ConString"].ConnectionString;

VB.NET code:

ConString = System.Configuration.ConfigurationManager.ConnectionStrings("ConString").ConnectionString

GetImages() method gets bytes from the BLOB column of the database and creates image files in the Images folder using ExecuteReader() of MySqlDataReader method. An overloaded version of ExecuteReader() method is used with a parameter of CommandBehavior.SequentialAccess because a BLOB field may contain data upto 4GB and it cannot be contained in a single row, it has to be retrieved as streams. After images are created, RunWorkerAsync() method of the BackgroundWorker control is called. It causes DoWork event of BackgroundWorker control to fire which binds images one by one in the PictureBox at an interval of 1000 milliseconds control to simulate like a slide show

C# code:

private void GetImages()
    MySqlConnection con = new MySqlConnection(ConString);
    MySqlCommand cmd;
    MySqlDataReader reader;

    int StudentID;

    string CmdString="SELECT StudentID, Image FROM Students";

    FileStream fs;
    BinaryWriter bw;
    int bufferSize = 1024; // Number of bytes to read at a time
    byte[] ImageData = new byte[bufferSize];
    long nBytesReturned, startIndex = 0;
    cmd = new MySqlCommand(CmdString, con);
    reader = cmd.ExecuteReader(CommandBehavior.SequentialAccess);
    if (!Directory.Exists("Images"))
    while (reader.Read())
        StudentID = reader.GetInt32("StudentID");
        // Create image files in Images folder using bytes retrieved from the database
        fs = new FileStream("Images/Image_" + StudentID.ToString() + ".jpg", FileMode.OpenOrCreate, FileAccess.Write);
        bw = new BinaryWriter(fs);
        startIndex = 0;
        nBytesReturned = reader.GetBytes(
            1, // Column index of BLOB column
            startIndex, // Start position of the byte to read
            ImageData, // Byte array to recieve BLOB data
            0, // Start index of the array
            bufferSize // Size of buffer

        // Continue if total bytes are more than the buffer size
        while (nBytesReturned == bufferSize)
            startIndex += bufferSize;
            nBytesReturned = reader.GetBytes(1, startIndex, ImageData, 0, bufferSize); // Number of bytes returned is assigned to nBytesReturned
        bw.Write(ImageData, 0, (int)nBytesReturned - 1);

VB.NET code:

Private Sub GetImages()
  Dim con As MySqlConnection = New MySqlConnection(ConString)
  Dim cmd As MySqlCommand
  Dim reader As MySqlDataReader
  Dim StudentId As Integer
  Dim CmdString As String = "SELECT StudentID, Image FROM Students"
  Dim fs As FileStream
  Dim bw As BinaryWriter
  Dim BufferSize As Integer = 1024
'Array in VB.NET counts elements from 0(lower bound) to its given size(upper bound.
'So to declare array of 1024 elements its size has to be 1023
  Dim ImageData(BufferSize - 1) As Byte
  Dim nBytesReturned, StartIndex As Long
  cmd = New MySqlCommand(CmdString, con)
  reader = cmd.ExecuteReader(CommandBehavior.SequentialAccess)
  If (Directory.Exists("Images") = False) Then
  End If
  While (reader.Read())
    StudentId = reader.GetInt32("StudentID")
    fs = New FileStream("Images/Image_" + StudentId.ToString() + ".jpg", FileMode.OpenOrCreate, FileAccess.Write)
    bw = New BinaryWriter(fs)
    StartIndex = 0
    nBytesReturned = reader.GetBytes(1, StartIndex, ImageData, 0, BufferSize)
    While (nBytesReturned = BufferSize)
      StartIndex += BufferSize
      nBytesReturned = reader.GetBytes(1, StartIndex, ImageData, 0, BufferSize)
    End While
  End While
End Sub

Write following in Button click event to open form to add images to the database

C# code:

private void btnAddImage_Click(object sender, EventArgs e)
    Form1 frm1 = new Form1();

VB.NET code:

Dim frm1 As Form1 = New Form1()

Write following in DoWork and RunWorkerCompleted event of the BackgroundWorker control

C# code:

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    foreach (string imgFile in Directory.GetFiles("Images"))
        pictureBox1.BackgroundImage = Image.FromFile(imgFile);
        pictureBox1.BackgroundImageLayout = ImageLayout.Zoom;

VB.NET code:

Private Sub backgroundWorker1_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles backgroundWorker1.DoWork
  For Each img As String In Directory.GetFiles("Images")
    pictureBox1.BackgroundImage = Image.FromFile(img)
    pictureBox1.BackgroundImageLayout = ImageLayout.Zoom
End Sub

When DoWork event completes it is started again using RunWorkerAsync() method in the RunWorkerCompleted event of the BackgroundWorker. It runs slide show again from the start and it never ends

C# code:

private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)

VB.NET code:

Private Sub backgroundWorker1_RunWorkerCompleted(ByVal sender As System.Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles backgroundWorker1.RunWorkerCompleted
End Sub

0 thoughts on “How to retrieve images from MySQL database and display as a slide show in Windows Forms application using C# and VB.NET

  1. reyno

    your the man dude!! ^_^ thank you so much!

    i have a question 🙁 when i load twice the picture. there’s no picture in the pictureBox. 🙁 can you tell me what to do sir??


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