I can't actually remember it in detail now, but this was when I was 15 or 16. It was a database application; I guess mine would have been music lending.
I wonder if I still have the code. I definitely still wish I had the book.
I really enjoyed QBASIC because of the gentle way you were exposed to better programming practices; I've always admired that.
Five or six years later, my uni project was a BASIC-to-C transpiler for a simple dialect of BASIC as a teaching language with some specific language extensions for message-passing parallel programming. It had a simple IDE, too.
In some ways it is a shame BASIC itself is really gone; modern implementations only have a whisper of its original simplicity.
It isn't the same thing though.
In the UK I gather kids are taught Scratch and Python in an overlapping fashion, so they see the structure on the Scratch view and then have a better chance of understanding how the code works without being thrown off by the symbols.
This is probably better in a pedagogical sense, and I am sure Scratch programmers have a better early understanding of flow control and things like loop termination conditions than BASIC programmers did; Scratch makes it more physical.
But it does lose that absolute immediacy of being able to type simple words onto an empty screen and see it do things.