Sincerely, i think doing such thing will be very hard especially for beginners. Even if you find a solution for the database and reading data from the phone storage there’s no direct way to check if two files are the same, and you want to check one from the phone and the other on the database and that make it very harder.
I think you can use Filey extension by @vknow360 to encode the malicious package and return it as string to save it to the database then encode the file you want from the phone and check if they’re the same. But the question is HOW would you know which file to encode as there’s many possibilities, any file on the phone may be one of the malicious ones. But i think i have a solution for that too, the common thing between two identique files is the size, retrieve the size of the file you want to check and if it’s the same as one of the malicious packages add it to the check list. And here we have another problem, would you use the size method on EVERY file in the phone? That may take a while, especially when the phone contains many files, but there’s a solution. Another common things between two identique files is their extension, search for files with that extension in the phone then check their sizes and if some of them may be malicious use the encoding method to check if they’re equal. For the database you can use Firebase from Google which is not very securised but free and easy to use since Kodular implemented components to handle it, or using MySQL which will be hosted on your own domain and use it with Web component or some extensions. It’s VERY hard but NOT impossible, you have to search in the community and documentation, try things by yourself and learn by yourself, and whenever you need help post here everyone will help as much as they can!
Recommended extensions:
Filey extension by @vknow360
File extension by @Taifun
And some intelligence, creativity and imagination! 
Before i start writing i was going to say it’s impossible and can’t be done in any way on any platform, but while writing i started getting solutions and realizing that it’s possible! 
