How to get TimeZone Offset in PHP

[caption id="attachment_768" align="alignnone" width="502"] timezone[/caption]

[sourcecode language="php"]
function getOffsetByTimeZone($localTimeZone)
{
$time = new DateTime(date('Y-m-d H:i:s'), new DateTimeZone($localTimeZone));
$timezoneOffset = $time->format('P');
return $timezoneOffset;
}

[/sourcecode]

Call this function passing a local time zone as a string.
eg.

getOffsetByTimeZone('America/New_York');

How to switch between Timezones in PHP

[caption id="attachment_768" align="alignnone" width="502"] timezone[/caption]

[Extracted from : http://www.mindfiresolutions.com/PHP-function-for-Time-Zone-conversion-56.php]

Convert from GMT to a local timezone

[sourcecode language="php"]
function ConvertGMTToLocalTimezone($gmttime,$timezoneRequired)
{
$system_timezone = date_default_timezone_get();

date_default_timezone_set("GMT");
$gmt = date("Y-m-d h:i:s A");

$local_timezone = $timezoneRequired;
date_default_timezone_set($local_timezone);
$local = date("Y-m-d h:i:s A");

date_default_timezone_set($system_timezone);
$diff = (strtotime($local) - strtotime($gmt));

$date = new DateTime($gmttime);
$date->modify("+$diff seconds");
$timestamp = $date->format("Y-m-d h:i:s A");
return $timestamp;

}
[/sourcecode]

Convert from local timezone to GMT

[sourcecode language="php"]
function ConvertLocalTimezoneToGMT($gmttime,$timezoneRequired)
{
$system_timezone = date_default_timezone_get();

$local_timezone = $timezoneRequired;
date_default_timezone_set($local_timezone);
$local = date("Y-m-d h:i:s A");

date_default_timezone_set("GMT");
$gmt = date("Y-m-d h:i:s A");

date_default_timezone_set($system_timezone);
$diff = (strtotime($gmt) - strtotime($local));

$date = new DateTime($gmttime);
$date->modify("+$diff seconds");
$timestamp = $date->format("Y-m-d h:i:s A");
return $timestamp;
}

[/sourcecode]

Convert from one local timezone to another local timezone


[sourcecode language="php"]
function ConvertOneTimezoneToAnotherTimezone($time,$currentTimezone,$timezoneRequired)
{
$system_timezone = date_default_timezone_get();
$local_timezone = $currentTimezone;
date_default_timezone_set($local_timezone);
$local = date("Y-m-d h:i:s A");

date_default_timezone_set("GMT");
$gmt = date("Y-m-d h:i:s A");

$require_timezone = $timezoneRequired;
date_default_timezone_set($require_timezone);
$required = date("Y-m-d h:i:s A");

date_default_timezone_set($system_timezone);

$diff1 = (strtotime($gmt) - strtotime($local));
$diff2 = (strtotime($required) - strtotime($gmt));

$date = new DateTime($time);
$date->modify("+$diff1 seconds");
$date->modify("+$diff2 seconds");
$timestamp = $date->format("Y-m-d h:i:s A");
return $timestamp;
}
[/sourcecode]
[sourcecode language="php"]
echo ConvertGMTToLocalTimezone("2013-03-16 14:28:00","Asia/Seoul")."
";
echo ConvertLocalTimezoneToGMT("2013-03-16 14:28:00","Asia/Seoul")."
";
echo ConvertOneTimezoneToAnotherTimezone("2013-03-16 14:28:00","Asia/Seoul","Australia/South");
[/sourcecode]

Dealing with Time Zones in PHP/MySQL

[caption id="attachment_768" align="alignnone" width="502"] timezone[/caption]

You might have experienced numerous problems when dealing with timezones. It is difficult to handle timezones when your web server and users are in different timezones. The condition become worse if the database server is in another timezone.

Let's see a simple way of storing date,time in database without messing up timezone related things. The datetime can be stored in GMT format without explicitly using a  specific timezone.

[sourcecode language="php"]
$gmtTime = gmdate("Y-m-d H:i:s", time());
[/sourcecode]

the timestamp value returned by time() function is stored in GMT format. This is neutral and can be stored in database without thinking timezone problems.

When querying data and make any date time comparisons you can convert it into a desired timezone using mysql built-in function CONVERT_TZ().

Following query can be used to retrive records added on a particular today with the consideration of a specific timezone.
This is based on 'America/Denver' timezone  ( -7:00).

[sourcecode language="php"]
SELECT *
FROM `audittrail`
WHERE date( CONVERT_TZ( datetime, '+0:00', '-7:00' ) ) = '2013-03-04 '

[/sourcecode]