using System;

using Newtonsoft.Json;

//using Newtonsoft.Json.Serialization;

using System.Collections.Generic;

using System.Linq;

using System.Collections.Generic;

using System.Data;

​

public class Program

{

    public static void Main()

    {

        DataTable table1 = GetDataTableOne();

        DataTable table2 = GetDataTableTwo();

        DataTable dtAux = new DataTable();

        dtAux.Columns.Add("groupID");

        dtAux.Columns.Add("cField");

        dtAux.Columns.Add("t1_field1");

        dtAux.Columns.Add("t1_field2");

        dtAux.Columns.Add("t2_field1");

        dtAux.Columns.Add("t2_field2");

        IEnumerable<DataRow> qry =

            from t1 in table1.AsEnumerable()

            join t2 in table2.AsEnumerable()

                on t1.Field<float>("cField") equals t2.Field<float>("cField")

            where t1.Field<int>("groupID") == 1

            select dtAux.LoadDataRow(new Object[]

                                     {

                                         t1.Field<int>("groupID"), t1.Field<float>("cField"), t1.Field<int>("field1"), 

                                         t1.Field<decimal>("field2"), t2.Field<int>("field1"), t2.Field<decimal>("field2")

                                     }, false);

        qry.CopyToDataTable();

​

        FiddleHelper.WriteTable(dtAux);

    }

​

    private static DataTable GetDataTableOne()

    {

        DataTable table = new DataTable();

        table.Columns.Add("pk", typeof(int));

        table.Columns.Add("groupID", typeof(int));

        table.Columns.Add("cField", typeof(float));

        table.Columns.Add("field1", typeof(int));

        table.Columns.Add("field2", typeof(decimal));

        DataRow row = table.NewRow();

        row["pk"] = 1;

        row["groupID"] = 1;

        row["cField"] = 0.5;

        row["field1"] = 10;

        row["field2"] = 5;

        table.Rows.Add(row);

        row = table.NewRow();

        row["pk"] = 2;

        row["groupID"] = 1;

        row["cField"] = 1;

        row["field1"] = 10;

        row["field2"] = 10;

        table.Rows.Add(row);

        row = table.NewRow();

        row["pk"] = 3;

        row["groupID"] = 1;

        row["cField"] = 2;

        row["field1"] = 10;

        row["field2"] = 20;

        table.Rows.Add(row);

        row = table.NewRow();

        row["pk"] = 4;

        row["groupID"] = 1;

        row["cField"] = 5;

        row["field1"] = 10;

        row["field2"] = 50;

        table.Rows.Add(row);

        return table;

    }

​

    private static DataTable GetDataTableTwo()

    {

        DataTable table = new DataTable();

        table.Columns.Add("pk", typeof(int));

        table.Columns.Add("groupID", typeof(int));

        table.Columns.Add("cField", typeof(float));

        table.Columns.Add("field1", typeof(int));

        table.Columns.Add("field2", typeof(decimal));

        DataRow row = table.NewRow();

        row["pk"] = 10;

        row["groupID"] = 1;

        row["cField"] = 0.5;

        row["field1"] = 20;

        row["field2"] = 10;

        table.Rows.Add(row);

​

        row = table.NewRow();

        row["pk"] = 11;

        row["groupID"] = 1;

        row["cField"] = 1;

        row["field1"] = 20;

        row["field2"] = 20;

        table.Rows.Add(row);

​

        row = table.NewRow();

        row["pk"] = 12;

        row["groupID"] = 1;

        row["cField"] = 2;

        row["field1"] = 20;

        row["field2"] = 40;

        table.Rows.Add(row);

        row = table.NewRow();

        row["pk"] = 13;

        row["groupID"] = 1;

        row["cField"] = 5;

        row["field1"] = 20;

        row["field2"] = 100;

        table.Rows.Add(row);

        return table;

    }

}