Unexpected Result while joining two datatables?

 object combinedrows = from dt1 in DsResults.Tables[0].AsEnumerable()
                           join dt2 in DsResults.Tables[1].AsEnumerable() on dt1.Field<string>("MethodName") equals dt2.Field<string>("MethodName")
                           select new { dt1, dt2 };
        DataTable finaldt = new DataTable("FinalTable");
        finaldt.Columns.Add(new DataColumn("sp",typeof(string)));
        finaldt.Columns.Add(new DataColumn("Method",typeof(string)));
        finaldt.Columns.Add(new DataColumn("Class",typeof(string)));
        finaldt.Columns.Add开发者_运维技巧(new DataColumn("BLLMethod",typeof(string)));
        DataRow newrow = finaldt.NewRow();
        finaldt.Rows.Add((DataRow)combinedrows);
        dataGridView5.DataSource = finaldt;

The above coding gives the result in the first column as follows: System.Linq.Enumerable+d__614[System.Data.DataRow,System.Data.DataRow,System.String,<>f__AnonymousType02[System.Data.DataRow,System.Data.DataRow]]

@Prem: After understanding your code i am sure you will get exception like

"Unable to cast object of type 'd__614[System.Data.DataRow,System.Data.DataRow,System.String,<>f__AnonymousType02[System.Data.DataRow,System.Data.DataRow]]' to type 'System.Data.DataRow'."

on

finaldt.Rows.Add((DataRow)combinedrows); line

so you must store Linq return result in var and then you can add row to new DataTable by loop.

your code should be

      var combinedrows = from dt1 in DsResults.Tables[0].AsEnumerable()
                              join dt2 in DsResults.Tables[1].AsEnumerable() on             dt1.Field<string>("MethodName") equals dt2.Field<string>("MethodName")
                              select new { dt1, dt2 };

        DataTable finaldt = new DataTable("FinalTable");
        finaldt.Columns.Add(new DataColumn("sp", typeof(string)));
        finaldt.Columns.Add(new DataColumn("Method", typeof(string)));
        finaldt.Columns.Add(new DataColumn("Class", typeof(string)));
        finaldt.Columns.Add(new DataColumn("BLLMethod", typeof(string)));
        DataRow newrow = finaldt.NewRow();           
        foreach (var row in combinedrows)
        {

            DataRow dataRow = finaldt.NewRow();
            dataRow.ItemArray = row.dt1.ItemArray;

             finaldt.Rows.Add(dataRow);
        }

try it out on the behalf of you i have checked it is running if not then post the error.

For to get only a particular column from DataTable you need to change LINQ like

 var combinedrows = from dt1 in DsResults.Tables[0].AsEnumerable()
                              join dt2 in DsResults.Tables[1].AsEnumerable() on dt1.Field<string>("MethodName") equals dt2.Field<string>("MethodName")
                           select new { td1Col = dt1.Field<string>("Tab1col2")}; 

and for Retrieving data you need to do:

       foreach (var row in combinedrows)
        {
            string value = row.td1Col.ToString();                                
        }

try this

var combinedrows = from dt1 in DsResults.Tables[0].AsEnumerable() 
                       join dt2 in DsResults.Tables[1].AsEnumerable() on dt1.Field<string>("MethodName") equals dt2.Field<string>("MethodName") 
                       select new { dt1, dt2 }; 
    DataTable finaldt = new DataTable("FinalTable"); 
    finaldt.Columns.Add(new DataColumn("sp",typeof(string))); 
    finaldt.Columns.Add(new DataColumn("Method",typeof(string))); 
    finaldt.Columns.Add(new DataColumn("Class",typeof(string))); 
    finaldt.Columns.Add(new DataColumn("BLLMethod",typeof(string))); 

        foreach (var row in combinedrows)
        {

            DataRow drow = finaldt.NewRow();
            drow.ItemArray = row.dt1.ItemArray;

             finaldt.Rows.Add(drow34);
        }

      dataGridView5.DataSource = finaldt;