Each user can set timezone

Hello, i guess your question has been answered.
I use this function ( from model) to convert any type of timestamp to the user date-time

PHP Code:

    function _set_timestamp($timestamp)
    {
        $timezone = $this->input->cookie('_timezone');
        $dt = new DateTime();
        $dt->setTimezone(new DateTimeZone($timezone));
        $dt->setTimestamp(strtotime($timestamp));
        return $dt->format("H:i d-m-Y");
    } 


so i take the server timestamp and the user timezone ( i have it on cookie) and i return the correct time according to user timezone

So i just keep the server timestamp+Database Timestamp the same and i just change the users.

Hello, i guess your question has been answered.
I use this function ( from model) to convert any type of timestamp to the user date-time

PHP Code:

    function _set_timestamp($timestamp)
    {
        $timezone = $this->input->cookie('_timezone');
        $dt = new DateTime();
        $dt->setTimezone(new DateTimeZone($timezone));
        $dt->setTimestamp(strtotime($timestamp));
        return $dt->format("H:i d-m-Y");
    } 


so i take the server timestamp and the user timezone ( i have it on cookie) and i return the correct time according to user timezone

So i just keep the server timestamp+Database Timestamp the same and i just change the users.

Don't need to use date_default_timezone_set?

Well, i dont do it i dont want to have different time on server different on user and database, so i keep the timestamp the same and i just change the timestamp where it needs.
I am not sure if its 100% correct or not

Well, i dont do it i dont want to have different time on server different on user and database, so i keep the timestamp the same and i just change the timestamp where it needs.
I am not sure if its 100% correct or not

In fact, before answering about DataTime, I was already using it, but I was doing it in a different logic. Your response opened my mind to think better. Sorted out! Thank you guys.