I am building a web application for used book trading and I am adding a feature to propose other book that would be interesting when they view an offer.
Currently the data that I store are the following (they are updated each time someone visit an offer) :
ISBN (book of the offer)
SessId (a unique id that everyone has when visiting the website)
NumberOfVisit (The number of time someone has view an offer of that book)
I also have access to some user update data which categorize the book by subject and course. It isn't necessarily up-to-date and precise, but it's nonetheless data.
What are the approach to list the most interesting books for a book ?