Merge gridview headers

Here is the code to merge header of the gridview

<asp:GridView ID="grvMergeHeader" runat="server">
<Columns>
<asp:BoundField DataField="DepartMentID"HeaderText="DepartMentID"SortExpression="DepartMentID" />
<asp:BoundField DataField="DepartMent"HeaderText="DepartMent"SortExpression="DepartMent" />
<asp:BoundField DataField="Name"HeaderText="Name"SortExpression="Name" />
<asp:BoundField DataField="Location"HeaderText="Location"SortExpression="Location" />
</Columns>
</asp:GridView>
protected void grvMergeHeader_RowCreated
(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.Header)
{
GridView HeaderGrid = (GridView)sender;
GridViewRow HeaderGridRow =
new GridViewRow(0, 0, DataControlRowType.Header,
DataControlRowState.Insert);
TableCell HeaderCell = new TableCell();
HeaderCell.Text = "Department";
HeaderCell.ColumnSpan = 2;
HeaderGridRow.Cells.Add(HeaderCell);

HeaderCell = new TableCell();
HeaderCell.Text = "Employee";
HeaderCell.ColumnSpan = 2;
HeaderGridRow.Cells.Add(HeaderCell);

grvMergeHeader.Controls[0].Controls.AddAt
(0, HeaderGridRow);
}
}