小编Luc*_*ucy的帖子

如何将SubGroup分组以创建大陆列表,其中每个大陆都有自己的县,每个国家/地区都有自己的城市,如此表

这是t-sql:

select Continent.ContinentName, Country.CountryName, City.CityName 
from  Continent
left join Country
on Continent.ContinentId = Country.ContinentId

left join City
on Country.CountryId = City.CountryId

和t-sql的结果:

我尝试了这个,但它以错误的方式对数据进行分组,我需要像上表一样进行分组

  var Result = MyRepository.GetList<GetAllCountriesAndCities>("EXEC sp_GetAllCountriesAndCities");

    List<Continent> List = new List<Continent>();


    var GroupedCountries = (from con in Result
                             group new
                             {


                                 con.CityName,

                             }

                             by new
                             {

                                 con.ContinentName,
                                 con.CountryName
                             }

            ).ToList();

    List<Continent> List = GroupedCountries.Select(c => new Continent()
    {

        ContinentName = c.Key.ContinentName,
        Countries = c.Select(w => new Country()
        {
            CountryName = c.Key.CountryName,

            Cities = c.Select(ww => new City() …

如果对象(国家/地区)不为null,我想返回一个视图.但是我收到错误"Not Not code paths返回一个值"

我的代码看起来像这样

public ActionResult Show(int id)
{
    if (id != null)
    {
        var CountryId = new SqlParameter("@CountryId", id);
        Country country = MyRepository.Get<Country>("Select * from country where CountryId=@CountryId", CountryId);
        if (country != null)
        {
            return View(country);
        }
    }

}