@Prog! - ASP.NET(C#) AJAX -

1. LINQ to SQL クラスを追加し、テーブルを追加する。
2. 関連付けを行う。Participating Properties：Table_1.ID -> Table_3.ID

using System;
using System.Linq;
using System.Data.Linq;
using System.IO;

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[ args)
        {
            using (DataClasses1DataContext db = new DataClasses1DataContext())
            {
                StreamWriter sw = new StreamWriter(@"d:\log.txt");
                sw.AutoFlush = true;
                TextWriter tw = TextWriter.Synchronized(sw);

                db.Log = tw;

                var rs = from t in db.Table_1 select t;

                foreach (var t1 in rs)
                {
                    foreach (var t3 in t1.Table_3)
                    {
                        Console.WriteLine("{0}:{1}", t1.ID, t3.FirstName);
                    }
                }
            }

            Console.Read();
        }
    }
}

上記の実行結果

SELECT [t0].[ID], [t0].[Number]
FROM [dbo].[Table_1] AS [t0]
-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.21022.8

SELECT [t0].[ID], [t0].[FirstName], [t0].[LastName], [t0].[Birthday]
FROM [dbo].[Table_3] AS [t0]
WHERE [t0].[ID] = @p0
-- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [0]
-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.21022.8

SELECT [t0].[ID], [t0].[FirstName], [t0].[LastName], [t0].[Birthday]
FROM [dbo].[Table_3] AS [t0]
WHERE [t0].[ID] = @p0
-- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [1]
-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.21022.8

SELECT [t0].[ID], [t0].[FirstName], [t0].[LastName], [t0].[Birthday]
FROM [dbo].[Table_3] AS [t0]
WHERE [t0].[ID] = @p0
-- @p0: Input Int (Size = 0; Prec = 0; Scale = 0) [2]
-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.21022.8

using System;
using System.Linq;
using System.Data.Linq;
using System.IO;

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[ args)
        {
            using (DataClasses1DataContext db = new DataClasses1DataContext())
            {
                StreamWriter sw = new StreamWriter(@"d:\log.txt");
                sw.AutoFlush = true;
                TextWriter tw = TextWriter.Synchronized(sw);

                db.Log = tw;

                DataLoadOptions dlo = new DataLoadOptions();
                dlo.LoadWith<Table_1>(t => t.Table_3);
                db.LoadOptions = dlo;

                var rs = from t in db.Table_1 select t;

                foreach (var t1 in rs)
                {
                    foreach (var t3 in t1.Table_3)
                    {
                        Console.WriteLine("{0}:{1}", t1.ID, t3.FirstName);
                    }
                }
            }

            Console.Read();
        }
    }
}

上記の実行結果

SELECT [t0].[ID], [t0].[Number], [t1].[ID] AS [ID2], [t1].[FirstName], [t1].[LastName], [t1].[Birthday], (
    SELECT COUNT(*)
    FROM [dbo].[Table_3] AS [t2]
    WHERE [t2].[ID] = [t0].[ID]
    ) AS [value]
FROM [dbo].[Table_1] AS [t0]
LEFT OUTER JOIN [dbo].[Table_3] AS [t1] ON [t1].[ID] = [t0].[ID]
ORDER BY [t0].[ID]
-- Context: SqlProvider(Sql2005) Model: AttributedMetaModel Build: 3.5.21022.8