private void CheckAndFillData()
        {
            UserService userService = new UserService();

            if (userService.CheckExisting())
            {
                userService.AddUser(new AppUser {
                    FirstName = "admin", Username = "******", LastName = "admin", Password = "******", Type = USER_TYPE.ADMIN
                });
                userService.AddUser(new AppUser {
                    FirstName = "doctor1", Username = "******", LastName = "doctor1", Password = "******", Type = USER_TYPE.DOCTOR
                });
                userService.AddUser(new AppUser {
                    FirstName = "doctor2", Username = "******", LastName = "doctor2", Password = "******", Type = USER_TYPE.DOCTOR
                });
                userService.AddUser(new AppUser {
                    FirstName = "doctor3", Username = "******", LastName = "doctor3", Password = "******", Type = USER_TYPE.DOCTOR
                });
                userService.AddUser(new AppUser {
                    FirstName = "doctor4", Username = "******", LastName = "doctor4", Password = "******", Type = USER_TYPE.DOCTOR
                });
                userService.AddUser(new AppUser {
                    FirstName = "patient1", Username = "******", LastName = "patient1", Password = "******", Type = USER_TYPE.PATIENT
                });
                userService.AddUser(new AppUser {
                    FirstName = "patient2", Username = "******", LastName = "patient2", Password = "******", Type = USER_TYPE.PATIENT
                });
                userService.AddUser(new AppUser {
                    FirstName = "patient3", Username = "******", LastName = "patient3", Password = "******", Type = USER_TYPE.PATIENT
                });
                userService.AddUser(new AppUser {
                    FirstName = "patient4", Username = "******", LastName = "patient4", Password = "******", Type = USER_TYPE.PATIENT
                });
            }

            AppointmentService appointmentService = new AppointmentService();

            if (appointmentService.CheckExisting())
            {
                appointmentService.Add(new AppAppointment()
                {
                    Doctor = "doctor1", Patient = "patient1", AppointmentTime = DateTime.Now, DiagnosisId = "-1"
                });
                appointmentService.Add(new AppAppointment()
                {
                    Doctor = "doctor2", Patient = "patient2", AppointmentTime = DateTime.Now, DiagnosisId = "-1"
                });
                appointmentService.Add(new AppAppointment()
                {
                    Doctor = "doctor3", Patient = "patient3", AppointmentTime = DateTime.Now, DiagnosisId = "-1"
                });
                appointmentService.Add(new AppAppointment()
                {
                    Doctor = "doctor4", Patient = "patient4", AppointmentTime = DateTime.Now, DiagnosisId = "-1"
                });
            }

            DiagnosisService diagnosisService = new DiagnosisService();

            if (diagnosisService.CheckExisting())
            {
                diagnosisService.Add(1, "Diagnosis1");
                diagnosisService.Add(2, "Diagnosis2");
                diagnosisService.Add(3, "Diagnosis3");
                diagnosisService.Add(4, "Diagnosis4");
            }
        }