protected void Button2_Click(object sender, EventArgs e)
    {
        string slotdate = TextBox1.Text;
        string slottime = "09:00-09:30";
        string username = Convert.ToString(Session["username"]);

        int result = obj.BookAppointment(username, slottime, slotdate);

        if (result == 0)
        {
            ScriptManager.RegisterStartupScript(Page, Page.GetType(), "ss", "<script>alert('Your Appointment Failed')</script>", false);
            Response.Redirect(ResolveUrl("appointment.aspx"));
        }
        else
        {
            ClientScript.RegisterStartupScript(Page.GetType(), "Message", "alert('Your appointment has been Scheduled');window.location='appointment.aspx';", true);
        }
    }