21、n Query(;int flag = cmd2.ExecuteN on Query(; if (flag 0 Labell.Text =成功提交客人信息! ; else Labell.Text =提交客人信息失败,查看输入是否正确!;conn. Close(; upDate(; delete(; private void upDate( string roomld = txtRoomld.Text.Trim(; string selectStr = ; string updateStr =...