How to store users timezone in mysql? [duplicate]

Answer 1

timezone string would be better than the offset or difference in hours because some timezones are subject of changes

http://www.php.net/manual/en/class.datetime.php

http://www.php.net/manual/en/class.datetimezone.php

for date/time math:

http://www.php.net/manual/en/class.dateinterval.php

http://www.php.net/manual/en/class.dateperiod.php

stop using php functions, oop classes are much better!