hello petrinjak,
for me, passing userID throught browser is bad for security reason.
when you, for example, create a URL like this
i can simply change /refresh the page by typing the URL (in the address bar of my browser) with:
and now... yeah.. i logged in as another user.
although you can also create a hash to identify current user:
it's still bad since you have to previously create unique key for each user and encode the info in a hash.
i'm +1 in using php session and/or cookie with hash. it will be much better in handling the security issue.
anyway, you're the decision maker. i'm here just a stranger..
