SQlite in QT... Where the heck is my database?

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 not a path. However I expected the file to be created either in the source directory, the build directory, or in my user directory. None of that happened, I can't find that file, finder can't, spotlight can't. But queries are working.. I can insert and select data from that table...

I connect to the same database when using "./DienstplanerDB.sqlite" but just... Where is it??

I feel dumb.