protected void showData_Click(object sender, EventArgs e)
{
  SqlConnection myConnection
   = new SqlConnection("Data Source=localhost;Initial Catalog=test;User ID=sa;password=sa");
  SqlDataAdapter ad = new SqlDataAdapter("SELECT * FROM booklist", myConnection);
  DataSet ds = new DataSet();
  ad.Fill(ds);
  this.gvShowData.DataSource = ds;
  this.gvShowData.DataBind();
}
//導出Excel表
protected void btnExportToExcel_Click(object sender, EventArgs e)
{
  Response.Charset = "GB2312";
  Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
  Response.AddHeader("Content-Type", "application/vnd.ms-excel");
  Response.AddHeader("Content-Disposition", "myexcelfile.xls");
  //以此編碼模式導出才不會出現亂碼
  StringWriter sw = new StringWriter();
  HtmlTextWriter htw = new HtmlTextWriter(sw);
  gvShowData.RenderControl(htw);
  Response.Write(sw.ToString());
  Response.End();
}
//一定要寫，否則出錯！！
public override void VerifyRenderingInServerForm(Control control)
{
}