they only need to be $ if you are getting htem from somewhere else. in your case they are not and this should work now.

$result = mysql_query("INSERT INTO nbalive_daybyday (GP, Nickname, PTS, FGM, FGA) VALUES ('GP".$i."' , 'Nickname".$i."' , 'PTS".$i."', 'FGM".$i."' , 'FGA".$i."')");


you should get

GP1 Nickname1 ...
GP2 Nickname2 ...
...


and so on. you don't get that?