Add a header to a gridview that groups some columns

protected void ReportGridView_DataBound(object sender, System.EventArgs e)
{
 Table ExtraTable = GridView1.Controls(0);
 GridViewRow ExtraGridViewRow = new GridViewRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal);
 TableHeaderCell ExtraTableHeaderCell1 = new TableHeaderCell();
 ExtraTableHeaderCell1.Text = "First 2 Columns";
 ExtraTableHeaderCell1.ColumnSpan = 2;
 ExtraGridViewRow.Cells.Add(ExtraTableHeaderCell1);
 TableHeaderCell ExtraTableHeaderCell2 = new TableHeaderCell();
 ExtraTableHeaderCell2.Text = "Next 3 Columns";
 ExtraTableHeaderCell2.ColumnSpan = 3;
 ExtraGridViewRow.Cells.Add(ExtraTableHeaderCell2);
 TableHeaderCell ExtraTableHeaderCell3 = new TableHeaderCell();
 ExtraTableHeaderCell3.Text = "Last 4 Columns";
 ExtraTableHeaderCell3.ColumnSpan = 4;
 ExtraGridViewRow.Cells.Add(ExtraTableHeaderCell3);
}