//get data from database
SqlDataAdapter da = new SqlDataAdapter("select * from emp", con);
DataSet ds = new DataSet();
da.Fill(ds);
//fill it in a gridview
GridView gd = new GridView();
gd.ID = "GridView1";
gd.DataSource = source;
gd.AutoGenerateColumns = true;
gd.DataBind();
//export that data to word/excel
Response.Clear();
Response.Buffer = true;
switch (type)
        {
            case ExportType.EXCEL:
                Response.ContentType = "application/ms-excel";
                Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.xls", "ExportedGridData"));
                break;

            case ExportType.WORD:
                Response.ContentType = "application/ms-word";
                Response.AddHeader("content-disposition", string.Format("attachment;filename={0}.doc", "ExportedGridData"));
                break;
        }
Response.Charset = "";
System.IO.StringWriter stringwriter = new StringWriter();

HtmlTextWriter htmlwriter = new HtmlTextWriter(stringwriter);
gd.RenderControl(htmlwriter);
Response.Write(stringwriter.ToString());
Response.End();