using System;

using System.Linq;

using System.Collections.Generic;

​

public class Table1

{

    public int Table1_id;

    public string Field1 = "This is Field1";

    public string Field2 = "This is Field2";

    public Table1(int id)

    {

        Table1_id = id;

    }

}

​

public class Table2

{

    public int Table2_id;

    public string FieldA = "This is FieldA";

    public string FieldB = "This is FieldB";

    public Table2(int id)

    {

        Table2_id = id;

    }

}

​

public class Program

{

    public static void Main()

    {

        var ListOfTable1 = new List<Table1>()

        {

        new Table1(0), new Table1(1), new Table1(2)}

​

        ;

        var ListOfTable2 = new List<Table2>()

        {

        new Table2(0), new Table2(0), new Table2(0)}

​

        ;

        var query =

            from t1 in ListOfTable1

            join t2 in ListOfTable2 on t1.Table1_id equals t2.Table2_id into j1

            from j2 in j1.DefaultIfEmpty()

            group j2 by new

            {

                t1.Table1_id,

                t1.Field1,

                t1.Field2

            } into ga

            select new

            {

                ga.Key.Table1_id,

                ga.Key.Field1,

                ga.Key.Field2,

                ManySubObjects = (from g in ga select g).FirstOrDefault() == null ? null : (from g in ga select new {

                    FieldA = g.FieldA,

                    FieldB = g.FieldB

                }).ToList()

            }

​

        ;

        foreach (var result in query)

        {

            if(result != null)

            {

                Console.Write(result.Table1_id + ", ");

                Console.Write(result.Field1 + ", ");

                Console.Write(result.Field2 + ", ");

                Console.Write((result.ManySubObjects == null ? 0 : result.ManySubObjects.Count()));                 

                Console.WriteLine();

            }

​

        }

    }

}