Help troubleshoot sql query in hook function please?

[Inetbiz]

<?php
function init_ClientAreaPage($vars) {
global $smarty;
$sql_product_rating = mysql_query("SELECT * FROM mod_products_reviews WHERE active= 1 AND productid=".$vars['productid']);
$votes = 0;
$rating = 0;
while ($productrating = mysql_fetch_array($sql_product_rating)) {
$votes ++;
$rating = $rating + $productrating["reviewrating"];
$avgrating = $rating / $votes;
}
$smarty->assign('revavg', $avgrating);
$smarty->assign('revrate', $rating);
add_hook("ClientAreaPage",1,"init_ClientAreaPage","");}
?>

[Inetbiz]

I'm getting empty results

[Inetbiz]

Data Sample:

INSERT INTO `mod_products_reviews` (`id`, `productid`, `userid`, `username`, `reviewtitle`, `reviewtext`, `reviewrating`, `reviewdate`, `active`, `adminreply`) VALUES
(1, 8, 106, 'John Doe', 'blah blah blah title', 'blah blah reviewtext', 5, 1313276172, 1, '');

[Inetbiz]

<?php


function init_ClientAreaPage($vars) {
global $smarty;
$sql_product_rating = mysql_query("SELECT * FROM mod_products_reviews WHERE active= 1 AND productid = ".$vars['product']['id']);


while ($productrating = mysql_fetch_array($sql_product_rating)) {
$votes = 0;
$rating = 0;
$votes ++;
$rating = $rating + $productrating["reviewrating"];   
}
$avgrating = $rating / $votes; 
$smarty->assign('revavg', $avgrating);
$smarty->assign('revrate', $rating);
$smarty->assign('votes', $votes);
}

add_hook("ClientAreaPage",1,"init_ClientAreaPage","");
?>

but now vote value is 1 and not the sum total or rows which is 6 for that product id.