省市县,区的查询（通过区开始）（导出的接口实现）

1.三张表的关系

2.接口的实现

public byte[] SCCToXlsx(IEnumerable<County> StateProvinceCC)
        {
            var properties = new[]
              {
                   new PropertyByName<County>("区/县", p => p.Name),
                   new PropertyByName<County>("城市", p =>GetCity(p.CityId)),
                   new PropertyByName<County>("省份", p =>GetStateProvinceName(GetStateProvince(p.CityId)))
            };
            return ExportToXlsx(properties, StateProvinceCC);
        }
        //通过区县id获取城市名称
        public string GetCity(int id)
        {
            return _cityService.GetCityById(id).Name;
        }

        /// <summary>
        /// 得到省的id
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public int GetStateProvince(int id)
        {
            return _cityService.GetCityById(id).StateProvinceId;//省的id
        }
        /// <summary>
        /// 通过id获取到省名称
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public string GetStateProvinceName(int id)
        {
            return _stateProvinceService.GetStateProvinceById(id).Name; ;
        }