Сравнение ячеек строкового типа ADOQuery

procedure TForm1.Button1Click(Sender: TObject);
var
login: string;
begin
If (Edit1.Text<>'') and (Edit2.Text<>'') then
begin
ADOQuery1.Active:=false;
ADOQuery1.SQL.Clear;
  ADOQuery1.Active:=true;
 ADOQuery1.Active:=false;
 ADOQuery1.Parameters.ParamByName('Ëîãèí').Value:=Edit1.Text;
 ADOQuery1.Active:=true;
   If ADOQuery1.RecordCount<>0 then
     begin
      If ADOQuery1.FieldByName('Ïàðîëü').AsString=Edit2.Text then
        begin
         login:=LowerCase(Edit1.Text);
         form2.Show;
  end;
end;
end;
end;

ADOQuery1.Active:=false;
ADOQuery1.SQL.Clear;
  ADOQuery1.Active:=true;
 ADOQuery1.Active:=false;
 ADOQuery1.Parameters.ParamByName('Логин').Value:=Edit1.Text;
 ADOQuery1.Active:=true;            // Что это за вкл/выкл?!

procedure TForm1.Button1Click(Sender: TObject);
var
I : integer;
Log : boolean;
begin
Log := False;
Form1.ADOQuery1.SQL.Clear;
Form1.ADOQuery1.SQL.Add('Select * From Tab');
Form1.ADOQuery1.Open;
Form1.ADOQuery1.First;
For I:=0 to Form1.ADOQuery1.RecordCount-1 do
Begin
IF (Form1.ADOQuery1.Fields.Fields[0].AsString=Form1.Edit1.Text) and (Form1.ADOQuery1.Fields.Fields[1].AsString=Form1.Edit2.Text) then
Log := true;
Form1.ADOQuery1.Next;
end;
 
if Log=True then Form2.ShowModal;
end;

While not Form1.ADOQuery1.Eof do
  begin
    ...
    Form1.ADOQuery1.Next;
  end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ADOQuery1.SQL.Text:='Select * From Tab Where [Логин]=:p1 AND [Пароль]=:p2';
  ADOQuery1.Parameters.ParamByName('p1').Value:=Edit1.Text;
  ADOQuery1.Parameters.ParamByName('p2').Value:=Edit2.Text;
  ADOQuery1.Open;
  if ADOQuery1.RecordCount>0 then Form2.ShowModal;
end;