> For the complete documentation index, see [llms.txt](https://docs.layraweb.com.tr/merhaba/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.layraweb.com.tr/merhaba/anadil/calismalar-ve-notlar/if/if-ile-bos-kontrol.md).

# İf İle Boş Kontrol

```visual-basic
if IsNull(Form.ad.ValueStr) or (Form.ad.ValueStr="") then
    MessageBox("Lütfen Ad giriniz.", "Model", MB_ICONSTOP)
    Return
  EndIf
```

{% content-ref url="/pages/nyoBbbnBVDfSOrWqRvUh" %}
[IsNull](/merhaba/anadil/kutuphane/diger/isnull.md)
{% endcontent-ref %}