Hi Aderson,
Thank you for your reply.
Yes, you can go either way, but I'm trying to find modules for which data exists in my app but which have been deleted in DNN.
Hence I created a list of all modules filtered by ModuleName to compare to the list of modules referenced by my app.
Then for those records with a null portalID, I tried working back to try and see which pages they exist on.
Now I can see they're on deleted pages.
Anyway, I don't think those records are doing any harm, so I will just ignore them.
Thank you once again.
Steve