What To Do When convert_tz Returns Null

If you're trying to use the mysql function convert_tz and it's returning null values:

mysql> select convert_tz(startTime, '+00:00', 'US/Eastern') from table where id = 12; 
+-----------------------------------------------+ 
| convert_tz(startTime, '+00:00', 'US/Eastern') | 
+-----------------------------------------------+ 
| NULL                                          | 
+-----------------------------------------------+ 
1 row in set (0.00 sec)

You need to run the following command on the server to load the timezone information:

$ mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql -u root -p mysql 
Enter password: 
Warning: Unable to load '/usr/share/zoneinfo/iso3166.tab' as time zone. Skipping it. 
Warning: Unable to load '/usr/share/zoneinfo/zone.tab' as time zone. Skipping it.

Then everything will work just fine:

mysql> select convert_tz(startTime, '+00:00', 'US/Eastern') from table where id = 12; 
+-----------------------------------------------+ 
| convert_tz(startTime, '+00:00', 'US/Eastern') | 
+-----------------------------------------------+ 
| 2014-12-13 08:00:00                           |
+-----------------------------------------------+ 
1 row in set (0.06 sec)