How Do I Draw A Line Chart Using Csv File With Different Format?

HTML Code:
<asp:label id="Label8" runat="server" text="Line Chart" xmlns:asp="#unknown"></asp:label>
                        <br />
                    <div id="chart_div8">
                        <asp:literal id="lt8" runat="server" xmlns:asp="#unknown"></asp:literal>
                    </div>

C# Code: 
public void Line_Chart1()
    {
        StringBuilder str4 = new StringBuilder();
        //string sql = "select * from tmp_feedback";
        string sql = "select itemid,round(avg(rating)) as rating from tmp_feedback group by itemid";
        DataSet ds = new DataSet();
        OracleDataAdapter adp = new OracleDataAdapter(sql, conn);
        adp.Fill(ds, "tmp_feedback");
        DataTable dt = new DataTable();
        dt = ds.Tables[0];
        try
        {
            adp.Fill(dt);
            str4.Append(@"<script type=text/javascript> google.load( *visualization*, *1*, {packages:[*corechart*]});
            google.setOnLoadCallback(drawChart);
            function drawChart() {
            var data = new google.visualization.DataTable();
            data.addColumn('string', 'ITEMID');
            data.addColumn('number', 'RATING');

            data.addRows(" + dt.Rows.Count + ");");

            Int32 i;
            for (i = 0; i <= dt.Rows.Count - 1; i++)
            {
                str4.Append("data.setValue( " + i + "," + 0 + "," + "'" + dt.Rows[i]["ITEMID"].ToString() + "');");
                str4.Append("data.setValue(" + i + "," + 1 + "," + dt.Rows[i]["RATING"].ToString() + ") ;");
            }
            str4.Append("   var chart = new google.visualization.LineChart(document.getElementById('chart_div8'));");
            str4.Append(" chart.draw(data, {width: 300, height: 300, title: 'Performance Rating',");
            str4.Append("vAxis: {title: 'Rating', titleTextStyle: {color: 'green'}}");
            str4.Append("}); }");
            str4.Append("</script>");
            lt8.Text = str4.ToString().TrimEnd(',').Replace('*', '"');
            conn.Close();
        }
        catch
        {

        }
        finally
        {
            conn.Close();
        }
    }