Changing timezone of a retrieved date in php - php

Question

I am retrieving a date in format of 2013-09-15 08:45:00 from the database, which is set in UTC and I need to change it to another dynamic timezone (based on user)
So far I've got
$datetime = $row->field_data_field_performance_times_field_performance_times_v;
$eventDate = DateTime::createFromFormat('Y-m-d H:i:s', $datetime, new DateTimeZone($user->timezone));
$performance_time = date_format($eventDate, 'l, j F, Y, H:i');
But it doesn't change the timezone. Any ideas what's wrong? It should be +2 hours in my case.

Answer 1

Your input datetime is in UTC, not user's timezone. So first you must create datetime object in UTC, and then set/change timezone to user's :
$dt = new DateTime('2013-09-15 08:45:00', new DateTimeZone('UTC'));
print_r($dt);
/*
DateTime Object
(
[date] => 2013-09-15 08:45:00
[timezone_type] => 3
[timezone] => UTC
)
*/
Now you have datetime in UTC timezone. If you wish to change timezone, just call ->setTimezone() on DateTime object :
$dt->setTimezone(new DateTimeZone('Europe/Berlin'));
print_r($dt);
/*
DateTime Object
(
[date] => 2013-09-15 10:45:00
[timezone_type] => 3
[timezone] => Europe/Berlin
)
*/
p.s. because input 2013-09-15 08:45:00 is in standard datetime format, you don't need to use DateTime::createFromFormat.