问题：

学生表，班级表，我要班级下面学生

A表，字段：AID,CLASS

B表,字段 :BID,BNAME,AID

A表数据

1 班级1

2 班级2

B表数据

1 学生1 1

2 学生2 1 

3 学生3 2

4 学生4 2

我想得到

CLASS NAME

班级1 学生1，学生2

班级2 学生3，学生4

这样怎么联合？

 

答案：

namespace ConsoleApplication1{    public class A    {        public int AID { get; set; }        public string Class { get; set; }    }    public class B    {        public int BID { get; set; }        public string BName { get; set; }        public int AID { get; set; }    }    class Program    {        static void Main(string[] args)        {            List A = new List()             {                 new A(){ AID = 1, Class="班级1" },                new A(){ AID = 2, Class="班级2" },            };            List B = new List()             {                 new B(){ BID = 1 , BName = "学生1", AID=1 },                new B(){ BID = 2 , BName = "学生2", AID=2 },                new B(){ BID = 3 , BName = "学生3", AID=1 },                new B(){ BID = 4 , BName = "学生4", AID=2 },            };            var lastResult = from p in A                             join q in B.GroupBy(x => x.AID).Select(x => new { Key = x.Key, Value = string.Join(",", B.Where(y => y.AID == x.Key).Select(y => y.BName)) })                             on p.AID equals q.Key                             select new                             {                                 CLASS = p.Class,                                 Name = q.Value,                             };            foreach (var item in lastResult)            {                Console.WriteLine(item);            }        }    }}