protected void ddComapanyFilter_SelectedIndexChanged(object sender, EventArgs e)
{
    DropDownList ddlLabTest = (DropDownList)sender;
    DataGridItem row = (DataGridItem)ddlLabTest.NamingContainer;
    DropDownList ddlAddLabTestShortName = (DropDownList)row.FindControl("ddlCountries");
    string sql = "select Data from RetPDF where Data = '" + ddlAddLabTestShortName.SelectedValue + "'";
    string conString = ConfigurationManager.ConnectionStrings["myConnectionString"].ConnectionString;
    SqlCommand cmd = new SqlCommand(sql);
    using (SqlConnection con = new SqlConnection(conString))
    {
        con.Open();
        cmd = new SqlCommand(sql, con);
        SqlDataReader dr = cmd.ExecuteReader();
        dr.Read();
        if (dr.HasRows)
        {
            byte[] lesson = (byte[])(dr[0]);
            String spathfile = System.IO.Path.GetTempFileName();
            //move from soures to destination the extension until now is .temp
            System.IO.File.Move(spathfile,
                System.IO.Path.ChangeExtension(spathfile, ".pdf"));
            //make it real pdf file  extension .pdf
            spathfile = System.IO.Path.ChangeExtension(spathfile, ".pdf");
            System.IO.File.WriteAllBytes(spathfile, lesson);
            ddlAddLabTestShortName.Items.Insert(0, new ListItem("Please Select PDF Files", ""));
            FileStream MyFileStream;
            long FileSize;
            MyFileStream = new FileStream(spathfile, FileMode.Open);
            FileSize = MyFileStream.Length;
            byte[] Buffer = new byte[(int)FileSize];
            MyFileStream.Read(Buffer, 0, (int)FileSize);
            MyFileStream.Close();
            Response.ContentType = "application/pdf";
            Response.Write("<b>File Contents: </b>");
            Response.BinaryWrite(Buffer);
            Response.Flush();
            Response.End();
            con.Close();
        }
    }
}