I know that setting the database name for a SQLite database means setting the path to the DB file.
I set it like this:

```
db.setDatabaseName("DienstplanerDB.sqlite");

```

* this is wrong
* this is not how it's done
* but I did it

And somehow it worked but I could not find the created file via Finder or Spotlight.

**EDIT**

It was in the app package, see my answer below for information.
Also, see Kuba Ober's and Gombat's answers for useful advice.