how can fatch image from database to picture box

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.NET4

hello
i am inserting an image in sql server and fatch this image to another web form.
but is show and error my code is
this code is use for insert image into sqldatabase column imgdata is varchar type:

OpenFileDialog dlg = new OpenFileDialog();
            DialogResult dlgRes = dlg.ShowDialog();
            if (dlgRes != DialogResult.Cancel)
            {
                //Set image in picture box
                pictureBox1.ImageLocation = dlg.FileName;
                //Provide file path in txtImagePath text box.
                txtimagepath.Text = dlg.FileName;
            }
  MemoryStream stream = new MemoryStream();
                pictureBox1.Image.Save(stream, System.Drawing.Imaging.ImageFormat.Jpeg);
                byte[] imageData = stream.ToArray();    

//and below code use for fatch image :
 SqlDataAdapter dataAdapter = new SqlDataAdapter(new SqlCommand("select imgdata from Joiningform where regno='" + regno + "'",con));
           DataSet dataSet = new DataSet();
            dataAdapter.Fill(dataSet);
            if (dataSet.Tables[0].Rows.Count == 1)
            {
                Byte[] data = new Byte[0];
                data = (Byte[])(dataSet.Tables[0].Rows[0]["imgdata"]);
                MemoryStream mem = new MemoryStream(data);
                pictureBox1.Image = Image.FromStream(mem);
                
            }  

but below exception is display on that line: DataSet dataSet = new DataSet(); System.InvalidOperationException was unhandled
Message=Fill: SelectCommand.Connection property has not been initialized.