private void btnAddSubscribers_Click(object sender, EventArgs e)
 {
     if (id_subscriber != -1)
     {
         // Edit Subscriber
         FablabDB.editSubscriber(id_subscriber,
                                 txtName.Text,
                                 txtSurname.Text,
                                 txtDateOfBirth.Text,
                                 txtAddress.Text,
                                 txtCity.Text,
                                 txtCountry.Text,
                                 txtPostcode.Text,
                                 txtTelephone.Text,
                                 txtEmail.Text);
     }
     else
     {
         // New Subscriber
         FablabDB.addSubscriber(txtName.Text,
                                txtSurname.Text,
                                txtDateOfBirth.Text,
                                txtAddress.Text,
                                txtCity.Text,
                                txtCountry.Text,
                                txtPostcode.Text,
                                txtTelephone.Text,
                                txtEmail.Text);
     }
     Close();
 }