/// <summary>
        /// dodanie doktora
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonAddDoctor_Click(object sender, EventArgs e)
        {
            var firstName   = textBoxNameDoc.Text;
            var surname     = textBoxSurnameDoc.Text;
            var salary      = textBoxSalaryDoc.Text;
            var specialty   = textBoxSpecialtyDoc.Text;
            var institution = textBoxInstitutionDoc.Text;

            Doctor doctor = new Doctor
            {
                FirstName     = firstName,
                LastName      = surname,
                Salary        = Int32.Parse(salary),
                Speciality    = specialty,
                InstitutionId = Int32.Parse(institution),
            };

            _doctors.Create(doctor);
            _doctors.Save();

            //Wyswietlenie zaktualizowane listy skoczkow
            LoadDoctors();
        }
        /// <summary>
        /// dodawanie pracownikow
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonAddStaff_Click(object sender, EventArgs e)
        {
            var firstName   = textBoxNameStaff.Text;
            var surname     = textBoxSurnameStaff.Text;
            var salary      = textBoxSalaryStaff.Text;
            var specialty   = textBoxProffesionStaff.Text;
            var institution = textBoxInstitutionStaff.Text;

            Staff staff = new Staff
            {
                FirstName     = firstName,
                LastName      = surname,
                Salary        = Int32.Parse(salary),
                Position      = specialty,
                InstitutionId = Int32.Parse(institution),
            };

            _staffs.Create(staff);
            _staffs.Save();

            //Wyswietlenie zaktualizowane listy skoczkow
            LoadStaffs();
        }
        /// <summary>
        /// Dodanie pacjenta
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonAddPatient_Click_1(object sender, EventArgs e)
        {
            SetPatientsDoctorsToNull();

            var patientFirstName = textBoxNamePatient.Text;
            var surname          = textBoxSurnamePatient.Text;
            var mainDoctor       = textBoxMainDoctorPatient.Text;
            var disease          = textBoxDiseasePatient.Text;

            Patient patient = new Patient
            {
                FirstName = patientFirstName,
                LastName  = surname,
                DoctorId  = Int32.Parse(mainDoctor),
                Doctor    = (Doctor)_doctors.GetById(Int32.Parse(mainDoctor)),
                Disease   = disease
            };

            _patients.Create(patient);
            _patients.Save();

            //Wyswietlenie zaktualizowane listy skoczkow
            LoadPatients();
        }