I have to filter a queryset by a dynamic value (which can be None): may I simply write:

```
filtered_queryset = queryset.filter(field=value)

```

or shall I check for None:

```
if value is None:
    filtered_queryset = queryset.filter(field__isnull=True)
else:
    filtered_queryset = queryset.filter(field=value)

```

Does the behaviour depend on the particular DBMS?