public static boolean deleteSQL(String date, String timestart,
			String timeend) {
		String sql = "delete from datetable where date='" + date
				+ "' and timestart='" + timestart + "' and timeend='" + timeend
				+ "'";
		try {
			statement = conn.prepareStatement(sql);
			statement.executeUpdate();
			return true;
		} catch (SQLException e) {
			System.out.println("ɾݿʱ");
			e.printStackTrace();
		} catch (Exception e) {
			System.out.println("ɾʱ");
			e.printStackTrace();
		}
		return false;
	}