Export multiple GridView header to excel in ASP.Net

Hi loraksa.t,

Please refer below sample.

HTML

<div>
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" AllowPaging="true"
        PageSize="10" OnRowCreated="GridView1_RowCreated" 
        onpageindexchanging="OnPageIndexChanging">
        <Columns>
            <asp:BoundField DataField="Department Id" HeaderText="Department Id" ItemStyle-Width="150px" />
            <asp:BoundField DataField="Department Name" HeaderText="Department Name" ItemStyle-Width="100px" />
            <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="100px" />
            <asp:BoundField DataField="Location" HeaderText="Location" ItemStyle-Width="100px" />
        </Columns>
    </asp:GridView>
    <br />
    <asp:Button ID="btnExport" runat="server" Text="Export To Excel" OnClick="ExportExcel" />
</div>

Namespaces

C#

using System.Data;
using System.IO;

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        this.BindGrid();
    }
}

private void BindGrid()
{
    DataTable dt = new DataTable();
    dt.Columns.AddRange(new DataColumn[] { new DataColumn("Department Id", typeof(int)), new DataColumn("Department Name", typeof(string)), new DataColumn("Name", typeof(string)), new DataColumn("Location", typeof(string)) });
    dt.Rows.Add(1, "IT", "A", "Delhi");
    dt.Rows.Add(1, "IT", "B", "Noida");
    dt.Rows.Add(2, "HR", "C", "Gurgaonv");
    dt.Rows.Add(2, "HR", "D", "Noid");
    dt.Rows.Add(3, "Admn", "E", "Noida");
    dt.Rows.Add(3, "Admin", "F", "Noid");
    this.GridView1.DataSource = dt;
    this.GridView1.DataBind();
}

protected void GridView1_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);
        HeaderGridRow.Attributes.Add("style", "text-align:center;font-weight:bold");
        this.GridView1.Controls[0].Controls.AddAt(0, HeaderGridRow);
    }
}

protected void OnPageIndexChanging(object sender, GridViewPageEventArgs e)
{
    this.GridView1.PageIndex = e.NewPageIndex;
    this.BindGrid();
}

protected void ExportExcel(object sender, EventArgs e)
{
    Response.Clear();
    Response.Buffer = true;
    Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.xls");
    Response.Charset = "";
    Response.ContentType = "application/vnd.ms-excel";
    using (StringWriter sw = new StringWriter())
    {
        HtmlTextWriter hw = new HtmlTextWriter(sw);

        //To Export all pages
        this.GridView1.AllowPaging = false;
        this.BindGrid();
        this.GridView1.RenderControl(hw);
        Response.Output.Write(sw.ToString());
        Response.Flush();
        Response.End();
    }
}

public override void VerifyRenderingInServerForm(Control control)
{
    /* Verifies that the control is rendered */
}

Screenshot