Get Top N Rows using Datatable object.

Assume that we have a Datatable filled,then write below code as:-

public DataTable getTop(DataTable dt, int n)
    {
        DataTable outputTable = dt.Clone();
        int i = 0;
        for (i = 0; i < n; i++)
        {
            if (dt.Rows.Count == i)
                return outputTable;

            outputTable.ImportRow(dt.Rows[i]);
        }
        return outputTable;
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {
            if (ViewState["Datatable"] != null)
            {
                DataTable dt = (DataTable)ViewState["Datatable"];
                int topNRows = Convert.ToInt32(TextBox1.Text);
                DataTable outputTable = getTop(dt, topNRows);
                gv.DataSource = outputTable;
                gv.DataBind();
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

Just pass any value in getTop method,which will fetch first n record.