用ADOQuery控件怎么进行数据的查询
procedure TForm1.Button2Click(Sender: TObject);
var
str:string;
begin
str:=dbcombobox1.Text;
with adoquery1 do
begin
connection:=adoconnection1;
close;
SQL.Add('select * from rtu');
sql.Add('where rtu_id=str');
execsql; //出错的地方 提示STR参数没有默认值
open;
end;