Listview 插入記錄前判斷textbox 值是否為空，如是取消保存

 protected void ListView1_ItemInserting(object sender, ListViewInsertEventArgs e)        {            TextBox HolidayTB = (TextBox)e.Item.FindControl("HolidayTextBox");            if (HolidayTB.Text.ToString()=="")                            {                e.Cancel = true;                Response.Write("<script type='text/javascript'>");                Response.Write("alert('Please input the date.');");                Response.Write("</script>");                //Response.Redirect("Holiday.aspx");            }        }