register

   	protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
   	{
   		PrintWriter out = res.getWriter();
		res.setContentType("text/html");

		try
		{
			res.setContentType("text/html");

			Class.forName("oracle.jdbc.driver.OracleDriver");

			Connection con = DriverManager.getConnection( "jdbc:oracle:thin:@localhost:1521:XE" , "system" , "connect" );

			String name = req.getParameter("name");
			String userName = req.getParameter("userName");
			String password = req.getParameter("password");
			String email = req.getParameter("email");
			String mobile = req.getParameter("mobile");

			checkUserValid(con,userName);

			PreparedStatement ps = con.prepareStatement("insert into table values( ?,?,?,? )");
			ps.setString(1, userName);
			ps.setString(2, password);
			ps.setString(3, email);
			ps.setString(4, mobile);

			int x = ps.executeUpdate();

			if(x>=1) {
				System.out.println("registration successful");
			} else {
				System.out.println("couldnot register");
			}

		}
		catch(Exception e) {
			e.printStackTrace();
		}
	}

	private boolean checkUserValid(Connection con,String userName) throws SQLException
	{
		Statement st = con.createStatement();
		ResultSet rs =	st.executeQuery("select * from table where userName = "+userName);

		try
		{
			if(rs.next())
			{
				return false;
			}
		}
		catch (SQLException e)
		{
			e.printStackTrace();
		}
		return true;
	}