从数据库获取二进制数据时参数无效异常

Question

我有一个名为＆＃34; Student＆＃34;以及名为＆＃34; GeneralStudent＆＃34;的表格。该表只包含两列名为＆＃34; Id＆＃34;和＆＃34;照片＆＃34;。我已经成功地将一些数据插入到＆＃34; GeneralStudent＆＃34;表。 Photos值是二进制数据。但是当我想通过以下代码检索图像时，会出现一条消息：

  

参数无效。

我该如何解决这个问题？

private void searchButton_Click(object sender, System.EventArgs e)
{
    SqlConnection con1 =new SqlConnection(@"server=RATHIN-PC\SQLEXPRESS;database=Student; integrated security=true");
    con1.Open();

    SqlDataReader myReader = null;
    SqlCommand myCommand = new SqlCommand( "select photo from GeneralStudent where id='" + searchTextBox.Text + "'", con1);

    if (searchTextBox.Text == "")
    {
        MessageBox.Show("Please Enter Studet Id.\nYou Entered Null Value\nThank You", "Error Message Window", MessageBoxButtons.OK,MessageBoxIcon.Error);
    }
    else
    {
        myReader = myCommand.ExecuteReader();
        myReader.Read();

        if (myReader.HasRows)
        {
            byte[] img = (byte[])(myReader["photo"]);

            if (img == null)
            {
                pictureBox3.Image = null;
            }
            else
            {
                MemoryStream mstrm = new MemoryStream(img);
                pictureBox3.Image = Image.FromStream(mstrm);
            }
        }
        else 
        {
            textBox1.Test= "Database is Empty";
        }
    }        
    myReader.Close();
}