Sorting and limiting datetime rows in datatable using linq

  private DataTable SortAndLimitRowsDateWise(DataTable dtTable, int datepositionintable, int returnrowscount)

    {

        DataTable dtReturnTable = new DataTable();

        DataTable dtMergeTable = new DataTable();

        if (returnrowscount <= dtTable.Rows.Count)

        {

            //ordering datewise the fields, it will convert automatically the datefields

            EnumerableRowCollection<DataRow> query = from order in dtTable.AsEnumerable()

                                                     orderby Convert.ToDateTime(order.Field<String>(datepositionintable))

                                                     select order;

            DataView view = query.AsDataView();

            dtMergeTable = view.ToTable();

            //selecting return rows count

            var dtTrec = from item in dtMergeTable.AsEnumerable()

                         select item;

            var topN = dtTrec.Take(returnrowscount);

            dtReturnTable = dtMergeTable.Clone();

            foreach (DataRow drrow in topN.ToArray())

            {

                dtReturnTable.ImportRow(drrow);

            }

        }

        return dtReturnTable;

    }