public ResultSet checkDoctor(String doctor_info) {
		try {
			// checking whether the user enters employee no or doctor name
			if (Helper.isInteger(doctor_info)) {
				String selectDoctorByNoQuery = "SELECT * FROM DOCTOR WHERE employee_no = "
						+ Integer.parseInt(doctor_info);
				rs = stmt.executeQuery(selectDoctorByNoQuery);
			} else {
				String selectDoctorByNameQuery = "SELECT * FROM PATIENT p, DOCTOR d "
						+ "WHERE p.health_care_no = d.health_care_no AND UPPER(name) = UPPER('"
						+ doctor_info + "')";
				rs = stmt.executeQuery(selectDoctorByNameQuery);
			}

		} catch (SQLException e) {
			System.out.println("Could not find the doctor.");
		}
		return rs;
	}