public LinkedList<Student> getAllStudent() {
		LinkedList<Student> ans = new LinkedList<Student>();
		String select = "SELECT * FROM STUDENT";
		try {
			ResultSet rs = stat.executeQuery(select);

			Student t;

			// ȡǰ
			Calendar now = Calendar.getInstance();
			now.setTime(new java.util.Date());
			final int year = now.get(Calendar.YEAR);

			// birthdayǳ,yearȥݵõ
			Calendar birthday = (Calendar) now.clone();
			while (rs.next()) {
				birthday.setTimeInMillis(rs.getDate("BIRTHDAY").getTime());
				t = new Student(rs.getString("NO").trim(), rs.getString("NAME")
						.trim(), year - birthday.get(Calendar.YEAR), rs
						.getString("Sex").trim(), rs.getDate("BIRTHDAY"), rs
						.getString("ADDRESS").trim(), rs.getString("TEL")
						.trim(), rs.getString("EMAIL").trim());
				ans.add(t);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return ans;
	}