public int getNumByLengthAndFirstNum(int length, String firstNum) {
		String sql = "select sum(num) from "+TABLE+" where length=? and combination like ?";
		Object[] args = new Object[] { length, firstNum+"%" };
		int[] argTypes = new int[] { Types.INTEGER, Types.VARCHAR };

		int n = 0;
		
		try {
			n = this.getJdbcTemplate().queryForInt(sql, args, argTypes);
		} catch (Exception e) {
			n = 0;
		}
		return n;
	}