Question about how to track and display time correctly

[JeremyCanada26]

I'm interested to know how other people keep track of time and also how they display time correctly back to the users. I'm using a third party API that I can tie into that actually gives me the userID of a user, their full name and the timezone for that user. After checking a few users data, this is an example data of what I'm working with.

 

userID: 234213412

first_name: foo

last_name: bar

timezone: -6

 

Basically when a user visits my web app, I create a new account for them and store the above data. Currently, I'm just fetching the result from time() and converting it into MySQL DateTime format and storing that into my database.

 

//get the current time as an integer
$php_timestamp = time();
//formats the time according to MySQL DateTime type
$this->mysql_formatted_time = date('Y-m-d H:i:s', $php_timestamp);

 

I would think the current way that I'm doing this is not very good because there is a possibility that I could introduce load balancing servers into the mix and they might not be located in the same region. Also, I would have no idea how to factor the time and modify it according to the timezone value.(in my above example, -6)

 

Can anyone help me decide what method I should use to keep all of my servers timestamps in sync and how to display the time to the end user so that it looks correct to them?

[harristweed]

Why not use GMT?

 

[JeremyCanada26]

sry, what exactly do you mean? how do I do it?

[DavidAM]

Personally, I think it best to store all times as GMT in the database. Then if you change servers (and the timezone changes) you don't have a mixed base for time data in the database.

 

To get the GMT value, use the time() function in php. In mysql you can use FROM_UNIXTIME(), or UTC_TIMESTAMP() for inserting/updating data.

 

When retrieving data use UNIX_TIMESTAMP() to convert a DATE/DATETIME column to a unix timestamp. Use date_default_timezone_set() to set the user's timezone, then use the date() function (in PHP) to format.

[JeremyCanada26]

Is there any way for me to do this using the -6 or -5 value that I already have along with the users data?

 

Ricky

[JeremyCanada26]

i still haven't figured out a good solution on how to factor in the value of -5 or -6 into the mix yet

[JeremyCanada26]

Can anyone provide an example for usage?

[jcbones]

Sure, here is a function that sets the timezone according to the gmt.

 

<?php 
//timezones function.
function setTimeZone($gmt) {
$times = array(
'0' => 'Europe/London',
'+1' => 'Europe/Rome',
'+2' => 'Asia/Jerusalem',
'+3' => 'Europe/Moscow',
'+4' => 'Asia/Baku',
'+5' => 'Asia/Ashgabat',
'+6' => 'Asia/Dhaka',
'+7' => 'Asia/Phnom_Penh',
'+8' => 'Asia/Hong_Kong',
'+9' => 'Asia/Seoul',
'+10' => 'Pacific/Port_Moresby',
'+11' => 'Pacific/Guadalcanal',
'+12' => 'Pacific/Fiji',
'-11' => 'Pacific/Midway',
'-10' => 'Pacific/Honolulu',
'-9' => 'America/Juneau',
'-8' => 'America/Los_Angeles',
'-7' => 'America/Denver',
'-6' => 'America/Chicago',
'-5' => 'America/New_York',
'-4' => 'America/St_Thomas',
'-3' => 'America/Buenos_Aires',
'-2' => 'Atlantic/South_Georgia',
'-1' => 'Atlantic/Cape_Verde'
);
if(!is_numeric($gmt)) { return false; }
date_default_timezone_set($times[$gmt]);
return true;
}


//usage of function
if(setTimeZone('+10')) {
echo date('m-d-Y g:i:s a');
}