help me understand now() for mysql current time and its time zones

问题

I need help understand how mysql can determine what the timezone is when I use the function now() (in mysql) when I insert into mysql database. The datetime format is YYYY-MM-DD 00:00:00. How do you get the user to get the right time at their location?

Does this question make sense?

Thank you for your time!

回答1:

now() is always refer to the server time from its timezone.

If you have both server and user timezone,
it can be done via function convert_tz,
such as

set @user_time_zone:='+02:00';
set @server_time_zone:='+08:00';

-- server timezone always come first
-- as now() is from server time
SELECT CONVERT_TZ(now(),@server_time_zone, @user_time_zone);

回答2:

Your datetime format YYYY-MM-DD 00:00:00 has no timezone information, so it's irrelevant which timezone the user is in.

NOW() uses the system's time.

回答3:

the now() function return system time determine your server's time and location! mysql can not do this for u, this is your program's job!!

回答4:

The system timezone is controlled by system_time_zone variable. you can view the current system time zone using the following in the mysql prompt

SELECT @@system_time_zone;

The system time zone can be changed using --timezone=timezone_name in the mysql server option

来源：https://stackoverflow.com/questions/7411647/help-me-understand-now-for-mysql-current-time-and-its-time-zones