In Aspx page

<asp:Button ID="but1" runat="server" OnClick="click_excel" />

In Cs Page:

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Data.SqlClient;

public partial class Sqltoexcel : System.Web.UI.Page

{

SqlConnection conn = new SqlConnection(connectionstring="Datasource=192.168.100.30\sqlserver;Database=IvinSample;User id=sa;password=IIT;")

DataTable dt = new DataTable();

protected void Page_Load(object sender, EventArgs e)

{

}

protected void click_excel(object sender, EventArgs e)

{

String str = "select * from Emp1";

SqlDataAdapter sda = new SqlDataAdapter(str, conn);

sda.Fill(dt);

exporttosql(dt);

}

public void exporttosql(DataTable dtdata)

{

HttpContext context = HttpContext.Current;

string attach = "attachment;filename=example.xls";

context.Response.ClearContent();

context.Response.AddHeader("content-disposition", attach);

context.Response.ContentType = "application/ms-excel";

string sep = "";

if (dtdata != null)

{

foreach (DataColumn dc in dtdata.Columns)

{

context.Response.Write(sep + dc.ColumnName);

sep = "\t";

}

context.Response.Write(System.Environment.NewLine);

foreach (DataRow dr in dtdata.Rows)

{

sep = "";

for (int i = 0; i < dtdata.Columns.Count; i++)

{

context.Response.Write(sep + "\"" + dr[i].ToString() + "\"");

sep = "\t";

}

context.Response.Write(System.Environment.NewLine);

}

context.Response.End();

}

labmesg.Text = "datatransfered";

labmesg.Visible = true;

}

}