yeh, sessions are a good way to do it.
I have shied away from cookies for my apps because some poeple have js switched off and so consistency is lost but, also, if they want to start something, they should finish it. the rewards are good because if they come back a few days later and have a cookie to 'pick up where they left off', whatever they are filling in for, may be gone/sold/booked.
you need to work out your product/site and know your customers needs, to be sure which way to go.
"The day you stop learning is the day you become obsolete"! - my late Dad.
Why do some people say "I don't know for sure"? If they don't know for sure then, they don't know!
Useful MySQL resource
Useful MySQL link