[RusMaXXX]

Код:

// сумма с циклом
procedure TMainForm.Button1Click(Sender: TObject);
var
  path: string;
  ITOG: integer;
begin
  path := ExtractFilePath(paramstr(0)) + 'BD.mdb';
  ADOTable1.Active := False;
  ADOConnection1.Connected := False;
  ADOConnection1.ConnectionString:='Provider=Microsoft.Jet.OLEDB.4.0;Data Source='+path+';Persist Security Info=False;';
  ADOConnection1.Connected:=true;
  ADOTable1.TableName := 'base';
  ADOTable1.Active := True;

  ITOG := 0;
  while not ADOTable1.Eof do
  begin
    ITOG := ITOG + ADOTable1.Fields[4].AsInteger;
    ADOTable1.Next;
  end;
  edITOG.Text := IntToStr(ITOG); // запись суммы в Edit
end;

// сумма SQL запросом
procedure TMainForm.Button2Click(Sender: TObject);
var
  path: string;
begin
  path := ExtractFilePath(paramstr(0)) + 'BD.mdb';
  ADOQuery1.Active := False;
  ADOQuery1.Close;
  ADOConnection1.Connected:=false;
  ADOConnection1.ConnectionString:='Provider=Microsoft.Jet.OLEDB.4.0;Data Source='+path+';Persist Security Info=False;';
  ADOConnection1.Connected:=true;
  ADOQuery1.SQL.Clear;
  ADOQuery1.SQL.Text:='SELECT SUM(value4) FROM base';
  ADOQuery1.Open;
  ADOQuery1.Active:=true;
  edITOG.Text := ADOQuery1.Fields[0].AsString; // запись суммы в Edit
end;

смотри вложение