>> so I am receiving the variables
May be you store these into some other variables before writing $query
$_POST is an array of $_POST, $_POST etc.
And this may be a reason for error if you are using $i as 0, 1, 2..
loop through $_POST and store into another array ppoints
( you are getting the POST, note that if you are starting from $i=0,1,2.., your initial $_POST[$i] may not be $_POST since $_POST is an array and there may be some FORM variables before you wrote name=<?=$i?>
in FORM, so another idea is to write name=<?='abc'.$i?>
UPDATE playerPoints SET week1='ppoints[$i]' WHERE player_id=2
I hope u'll resolve:)