delphi 中出现cannot perform this operation on a closed dataset问

delphi 中出现cannot perform this operation on a closed dataset问题procedure Tfrm_bmxx.FormShow(Sender:TObject);begindata1.ADOQYbmxx.Active:=false;with data1.ADOQYbmxx dobeginclose;sql.Clear;sql.text := 'select * from 部门表'; // sql.Add('select * from 部门表');open;data1.ADOQYbmxx.Active:=true;if data1.ADOQYbmxx.FieldByName('部门编号').Value= null thenbeginapplication.MessageBox('数据库中没有数据,请添加数据','提示',64);speedbutton1.Click;end; end;end;每次运行时点击dbgrid时出现此错误,且显示不了数据库里的信息.