Data storage container
I don't know what kind of container I choose to store data.
There is a list of universities, each university has a set of specialties, a set of courses for each specialty, and a list of subjects in each course.
The student selects his university, his specialty and his course, and this remains in the annex. Then he chooses which items to download, and each subject has a set of PDF files. I tried to do it through XML, which is downloaded from the server, created XML with a list of universities, university XML with a list of specialties and course numbers, but somehow it's not very flexible. In fact, I need to implement the Android application and make sure that the data container works also in case of expansion. I mean, it's XML editing now. Is it worth doing a database or is it possible to use a simple way to store these data?
I'm not sure I've got the right answer the author wants.
Do you need an ancient investment with "one to many"? It will allow for, for example, a sample of " which universities at which specialties are simultaneously studying X and Y subjects but not studying Z " .
Databases are well suited to store such data (and manipulation with them), yes. Doing the table for each substance and for an additional reference table for the relationship. If desired, the external keys (foreign keys) between the tables could be further wrapped in order, for example, to eliminate references to non-existent nature.