LINQ:分组子组 [英] LINQ: Grouping SubGroup

问题描述

如何对子组进行分组以创建大洲列表，其中每个大洲都有自己的县，每个国家都有自己的城市(如该表所示)

How to group SubGroup to create list of Continents where each Continent has it own counties and each country has its own cities like this table

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:

我尝试了此操作，但是它以错误的方式对数据进行分组，因此我需要按照上表进行分组

I tried this but it groups the data in wrong way i need to group exactly like the above table

  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()
            {
                CityName = ww.CityName
            }
            ).ToList()

        }).ToList()


    }).ToList();

推荐答案

您需要按大陆将所有内容分组，按国家/地区将城市分组，并按城市将国家/地区分组:

You need to group everything by continent, these by country and the countries by city:

List<Continent> List = MyRepository.GetList<GetAllCountriesAndCities>("EXEC sp_GetAllCountriesAndCities")
    .GroupBy(x => x.ContinentName)
    .Select(g => new Continent 
    {
        ContinentName = g.Key,
        Countries = g.GroupBy(x => x.CountryName)
                     .Select(cg => new Country 
                     {
                         CountryName = cg.Key,
                         Cities = cg.GroupBy(x => x.CityName)
                                    .Select(cityG => new City { CityName = cityG.Key })
                                    .ToList()
                     })
                     .ToList()
    })
    .ToList();

这篇关于LINQ:分组子组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！