PHP, calculate time since added - php

Question

I have this function that calculates the time elapsed since a row was added into a database:
function added_on($time){
$now = time();
$time = $now - $time;
$blocks = array (
31536000 => 'year',
2592000 => 'month',
604800 => 'week',
86400 => 'day',
3600 => 'hour',
60 => 'minute',
1 => 'second'
);
foreach ($blocks as $unit => $size) {
if ($time < $unit)
continue;
$nrOfUnits = floor($time / $unit);
return $nrOfUnits.' '.$size.(($nrOfUnits>1)?'s':'');
}
}
The problem with this is that is not accurate, i.e has an error of about 7 hours behind.
When called on a current time, it returns like: added 7 hours ago.
Function is called as:
$posted_on = strtotime($row['created_at']);
echo 'added '.added_on($posted_on).' ago';
Where $row['created_at'] is MySQL Date type
thank you

Answer 1

At first blush I'm guessing different time zones. A different way to accomplish the same task in pure MySql follows:
select time_to_sec(timediff(now(), created_at)) as seconds_ago from `table_name`
To help you debug more you can check and set the timezone of the mysql server with the following (docs):
-- Check the global and session time_zone settings
select ##global.time_zone, ##session.time_zone;
-- Set the time zone to GMT -5 hours (EST):
set SESSION time_zone = '-5:00';