private void AddDistrict_Click(object sender, EventArgs e)
        {
            var district = new StateOrDistrict(InputDistrict.Text, TableDistrict, ListState.SelectedItem.ToString());

            district.Add(sqlConnection);

            ListDistrict.DataSource = StateOrDistrict.LoadListState(TableDistrict, ListState.SelectedItem.ToString(), sqlConnection);
            InputDistrict.Text      = "";
        }
        private void AddState_Click(object sender, EventArgs e)
        {
            var state = new StateOrDistrict(InputState.Text, TableState, ListCountry.SelectedItem.ToString());

            state.Add(sqlConnection);

            ListState.DataSource = StateOrDistrict.LoadListState(TableState, ListCountry.SelectedItem.ToString(), sqlConnection);
            InputState.Text      = "";
        }