timezone in mysql - now()

[aopen]

I'm using PHP with MySQL.

In the php code I set timezone using this function (date_default_timezone_set). But when I query and use timestamp or now() I get timestamp of server.

How to change mysql settings - so it won't user server clock?

Can I set timezone in MySQL?

[Installer]

Some or all of your options are detailed here.

[aopen]

mysql> SELECT @@global.time_zone, @@session.time_zone;
+--------------------+---------------------+
| @@global.time_zone | @@session.time_zone |
+--------------------+---------------------+
| SYSTEM | SYSTEM |
+--------------------+-------------------

How I can change time_zone to 'America/Los_Angeles'?
mysql> set time_zone='America/Los_Angeles';
ERROR 1298 (HY000): Unknown or incorrect time zone: 'America/Los_Angeles'

Thanks