日期时间时区mysql和php计算

Question

i have a question about processing valid date and time with time zone in applications using php and mysql.

mysql datetime object dosnt save timezone information. so i cant save many timezones in database. but in php applications each user can be has own time zone using php script date_default_timezone_set() ... so problem will be appear when.

user     timezone            lastchange
user1    UTC                 2012-01-01 12:20:00
user2    Australia/Melbourne 2012-01-01 12:19:00

but in calculation user2 lastchange is lower than user1 lastchange but in real world is negative.

what's the best solution for solve this issue?

Answer 1

I think you have to stock the time to your timezone, and when you want to display it, use the function : date(), and pass it a timestamp corrected to the timezone of the user ! mktime will help you with the timestamp, because you can pass to it negative integer to back in time ;)