Question

I’ve a bunch of data stored in a mysql database as a bunch of unix style timestamps (in UTC). Previously, these have been formatted via Perl’s gmtime(). It seems that MySQL’s FROM_UNIXTIME() function tries to be helpful, and correct for daylight savings, but I really don’t want it to.

Is there a nice handy method to convert the results from the system timezone (GMT/BST) to UTC or alternately determine if DST was in effect for a particular time?

Answer 1

Have you tried:

mysql> SELECT NOW();
+---------------------+
| NOW()               |
+---------------------+
| 2011-04-04 22:54:13 |
+---------------------+
1 row in set (0.00 sec)

mysql> set @var = unix_timestamp(NOW());
Query OK, 0 rows affected (0.00 sec)

mysql> SET time_zone='+00:00';
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT NOW();
+---------------------+
| NOW()               |
+---------------------+
| 2011-04-04 20:54:23 |
+---------------------+
1 row in set (0.00 sec)

mysql> SELECT FROM_UNIXTIME(@var);
+---------------------+
| FROM_UNIXTIME(@var) |
+---------------------+
| 2011-04-04 20:54:17 |
+---------------------+
1 row in set (0.02 sec)

If you want to use named timezones, you can see this page for more information, and how to fill the timezone tables on your system.