I'm setting up a page that pulls information from a database. The customer wants this

List of links that start (do not need to come from db)

(visitor clicks on one of the links)

Visitor would then get this tabulated format:

List of starting links ---> List of secondary links

And so on to a third tier of links

I started using $_GET variables for this, but run into issues trying to sanitize the input properly because of the large amount of variables that will end up being strings because I'm just pulling data from the db and trying to set it as a variable. They do not want a submit button, just click links. Should I just continue setting get variables as something like "General Studies" and sanitize the strings? Any ideas?