What I would like to do is essentially check whether or not a user has clicked a certain link on a page. The idea behind the functionality is that a user can click "Thanks!" on a post created on the website, but they can only submit one "Thanks!" per post.
I have no problem creating a simple click counter for the "Thanks!" button, and save the count to a database using PDO, but I am not sure how I can assign a click to the user who's session is active.Also, posts are constantly being added to the site, so I would need a system which would scale to more posts automatically.
Any guidance is appreciated, thanks!
Note: I know I have not put any example code, but I believe this is simple enough for a good programmer to grasp quickly.
EDIT On further thought, the IP can not be used to distinguish users, as this website will be used by many people on the same IP.