do not display dublicated entries

Hello all, I have created a simple webtracer for my website and I save some info on mysql database. table = tracker FIELDS ip day month year session_id browser of visitor page that was visited What I would like to do next, is simple to create an output of that database with the last time that every different IP has visited my website. the best output I have at the moment is: $query = "SELECT ip,day,month,year FROM tracker WHERE page = 'index' ORDER BY tracker.year DESC , tracker.month DESC , tracker.day DESC LIMIT 0,20 "; The problem is that I want to Keep for each different IP the fisrt entry that is found on this output I get. therefore I would say that the output would represent the last visit of each different user on my website. do you know of a php or sql trick to avoid entries that containt the same IP entries ? Thanks in advance for the help. Nikos.