title: rating system: storing username/ip in db or cookies?
body: <p>I'm creating a simple thumbs up/down rating system. A user can simply click up or down, and total number of thumb ups/down is stored in db. I don't want the user to be able to vote multiple times However, I don't want to store the IP address or username of the user to check if it has already voted or not, because i think it will be pretty much mess in database. I'm confused, if I can use some alternative approach (for example storing the username,and item name in the cookies, so that it can prevent at least for some time.
  Please let me know if storing (username, item-id) in db is good approach or storing in browser cookies? Thanks.</p>