protected void lbtndel_Click(object sender, EventArgs e)
    {
        int j = 0;

        for (int i = 0; i < gvrequest.Rows.Count; i++)
        {
            CheckBox cb = (CheckBox)gvrequest.Rows[i].FindControl("cbsel");
            if (cb.Checked)
            {
                j = j + 1;
                int     id        = int.Parse(gvrequest.DataKeys[i].Value.ToString());
                request myRequest = new request();
                myRequest.DeleteRequest(id);
            }
        }
        if (j == 0)
        {
            Response.Write("<script>alert('请选择要撤销的请求信息')</script>");
        }
        else
        {
            BindData();
        }
    }