public static int recentChallengesCount(Statement stmt, int user_id) {
		Calendar cal = Calendar.getInstance();
		cal.add(Calendar.DATE, -7);
		java.util.Date aWeekAgoDate = cal.getTime();
		String aWeekAgo = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(aWeekAgoDate);
		try {
			ResultSet rs = stmt.executeQuery("SELECT COUNT(*) AS count FROM challenges WHERE challenged_user = " + user_id + " AND challenged_on > '" + aWeekAgo + "'");
			rs.first();
			return rs.getInt("count");
		} catch (SQLException e) {
			e.printStackTrace();
			return 0;
		}
	}