var dataTable = new DataTable("Currency");
            dataTable.Columns.Add(new DataColumn("RateDate", typeof(DateTime)));
            dataTable.Columns.Add(new DataColumn("Currency", typeof(string)));
            dataTable.Columns.Add(new DataColumn("Rate", typeof(decimal)));

            var row1 = dataTable.NewRow();
            row1["RateDate"] = DateTime.Parse("2020-01-01");
            row1["Currency"] = "EUR";
            row1["Rate"] =80.0;
            dataTable.Rows.Add(row1);

            var row2 = dataTable.NewRow();
            row2["RateDate"] = DateTime.Parse("2020-01-01");
            row2["Currency"] = "USD";
            row2["Rate"] = 70.0;
            dataTable.Rows.Add(row2);

            var row3 = dataTable.NewRow();
            row3["RateDate"] = DateTime.Parse("2020-01-02");
            row3["Currency"] = "EUR";
            row3["Rate"] = 81.0;
            dataTable.Rows.Add(row3);

            var row4 = dataTable.NewRow();
            row4["RateDate"] = DateTime.Parse("2020-01-02");
            row4["Currency"] = "USD";
            row4["Rate"] = 71.0;
            dataTable.Rows.Add(row4);