【高分在线急等】LINQ查询问题，代码已贴出

Question

-----------------Sqlserver表数据Category--------------------------
表结构：
ID   Category    
1      分类1   
2      分类2  
3      分类3  
4      分类4  
5      分类5   -----------------Sqlserver表数据Detail--------------------------
表结构：
ID   CategoryID    Name    
1      1           子类1   
2      1      子类23      2           子类3
4      2           子类3 
5      2           子类3--------------需用Linq查出结果----------------------------------   [{"CategoryName":"分类1",
  "DetailCount":2,
           Items:[{"ItemName":"子类1",Count:1}
  {"ItemName":"子类2",Count:1}]
     }
    {"CategoryName":"分类2",
  "DetailCount":3,
           Items:[{"ItemName":"子类3",Count:3}]
     }
   ]-------------已建立的实体类-------------------------------------
class Category
//大类名称
public string CategoryName;
//下面子类总数
public int    DetailCount;
//子类list
public List<Detail> item;class Detail
//子类名称
public string ItemName;
//子类个数
public int    Count;
LINQ类

Answer 1

var query = from c in Category
            join d into Detail
            on c.id equals d.CategoryID into g
            select new { CategoryName = c.Category, DetailCount = g.Count(), Items = g };

Answer 2

//所有Category集合
            List<LogCategory> category = GetLogCategory().ToList();
//所有LogDetail集合
            List<LogDetail> detail = GetLogDetail().ToList();
                         
            var result = from c in category
                         join d into detail
                         on c.ID == d. into g
                         select new {CategoryName = c.Category, DetailCount = g.Count(), Items = g };这样好像有错误 大侠

Answer 3

    class Program
    {
        static void Main(string[] args)
        {
            List<Category> categorys = new List<Category>
                                      {
                                            new Category {Id=1,Name="分类1"},
                                            new Category {Id=2,Name="分类2"},
                                            new Category {Id=3,Name="分类3"},
                                            new Category {Id=4,Name="分类4"},
                                            new Category {Id=5,Name="分类5"},
                                      };
            List<Detail> details = new List<Detail>
                                       {
                                           new Detail{Id=1,CategoryId=1,Name="子类1-1"},
                                           new Detail{Id=2,CategoryId=1,Name="子类1-2"},
                                           new Detail{Id=3,CategoryId=2,Name="子类2-1"},
                                           new Detail{Id=4,CategoryId=2,Name="子类2-2"},
                                           new Detail{Id=5,CategoryId=3,Name="子类3-1"},
                                           new Detail{Id=6,CategoryId=3,Name="子类3-2"},
                                           new Detail{Id=7,CategoryId=3,Name="子类3-3"},
                                       };
            var query = details.GroupBy(g => new { g.CategoryId }).Select(s => new Result
                                                                                   {
                                                                                       CategoryName = categorys.FirstOrDefault(f => f.Id == s.Key.CategoryId).Name,
                                                                                       DetailCount = details.Where(w => w.CategoryId == s.Key.CategoryId).Count(),
                                                                                       Items = details.Where(w => w.CategoryId == s.Key.CategoryId).ToList()
                                                                                   });        }
    }
    public class Result
    {
        public string CategoryName { get; set; }
        public Int32 DetailCount { get; set; }
        public List<Detail> Items { get; set; }
    }    public class Category
    {
        public Int32 Id { get; set; }
        public string Name { get; set; }    }
    public class Detail
    {
        public Int32 Id { get; set; }
        public Int32 CategoryId { get; set; }
        public string Name { get; set; }
    }