protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		try{
			String[] categories=request.getParameterValues("category");
			HttpSession session=request.getSession(false);
			StudentBean bean = (StudentBean)session.getAttribute("person");
			StudentDao dao=new StudentDao();
			System.out.println("Student Id:: "+bean.getStudentId());
			System.out.println("User Id:: "+bean.getUserid());
			dao.deleteSubscribedCategories(bean.getStudentId());
			for(String cat:categories){
				dao.studentCategorySubscribe(bean.getUserid(), cat);
			}
			fetchSubscribedCategoryList(session);
			RequestDispatcher rd=request.getRequestDispatcher("thankyouupdate.jsp");    
			rd.include(request,response); 
		}catch(Exception e){
			e.printStackTrace();
		}
	}