Query:
SELECT SubdivisionCode, SubdivisionName, IsDefault
FROM CountrySubdivisions
WHERE CountryCode = :CountryCode


procedure TForm1.Button1Click(Sender: TObject);
begin
  DBISAMQuery1.Close;
  DBISAMQuery1.ParamByName('CountryCode').AsString := 'CA';
  DBISAMQuery1.RequestLive := True;  //if false no error raised
  DBISAMQuery1.Open;

     if DBISAMQuery1.locate('IsDefault',True,[]) then
       showmessage('Yes')
     else
       showmessage('No');

  DBISAMQuery1.Close
end;