protected void Btn_Approve_Click(object sender, EventArgs e)
        {
            string      remark = TextBox_Remarks.Text;
            Requisition req    = reqDAO.findRequisitionByrequisitionId(reqID);

            reqDAO.updateRequisition(req, remark, "Approved");
            //send feedback email and notification to employee
            SA45_Team09_LogicUEntities context = new SA45_Team09_LogicUEntities();
            string headID          = Session["loginID"].ToString();
            string headName        = Session["loginName"].ToString();
            string staffID         = req.staffID;
            string staffName       = context.DeptStaffs.Where(x => x.staffID == staffID).Select(x => x.staffName).ToList().First();
            string requisitionDate = req.requisitionDate.ToString();

            NotificationDAO nDAO = new NotificationDAO();

            nDAO.addDeptNotification(staffID, headName + " approved your requisition on " + requisitionDate, DateTime.Now);

            Email email = new Email();

            email.sendFeedBackEmailToEmployee(staffName, headName, requisitionDate, "Approved");

            Response.Redirect("./DH_ViewPendingRequisition.aspx");
        }