Ограничить ввод в EDIT

 procedure TForm4.Edit1KeyPress(Sender: TObject; var Key: Char);
 begin
case key  of
'0'..'9',#8,',':;
else
key:=#0;

  end;

procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
 var  vrPos, vrLength, vrSelStart: byte;
const
  I: byte = 1; //2 символа после decimalseparator-а
begin
  with Sender as TEdit do
  begin
    vrLength := Length(Text);
    vrPos := Pos(decimalseparator, Text);
    vrSelStart := SelStart;
  end;
  case Key of
    '0'..'9':
      begin
        if (vrPos > 0) and (vrLength - vrPos > I) and (vrSelStart >= vrPos) then
          Key := #0;
      end;
    ',', '.':
      begin
        if (vrPos > 0) or (vrSelStart = 0) or (vrLength = 0) then
          Key := #0
        else
          Key := decimalseparator;
      end;
    #8: ;
  else
    Key := #0;
  end;
end;

procedure TForm1.Edit1Change(Sender: TObject);
begin
  if Edit1.Text <> '' then
    Button1.Enabled := StrToInt(Edit1.Text) <=
      DBEdit1.DataSource.DataSet.FieldByName('Поле').AsFloat;
end;