Question

Hi I’m so confused with this UTC and GMT

I’m inserting in MySQL table as ex column “event_date” like “2010-07-01 23:50:00” (datetime) my client asking an option in front end as GMT +1 GMT +2 GMT -1 GMT -2 …etc if I select any option GMT +2 the event_date will filter/list according to the GMT +2.

I have no idea how to proceed and after googling I found this

CONVERT_TZ( `field_eventdate_value` , '+00:00', '+10:00' )

and whether it works well and my client gave me a sample URL to check like this

http://www.forexpros.com/economic-calendar/

I’m working with drupal nodes

Thanks in advance,

Gobi

Answer 1

The docs are an excellent read.

CONVERT_TZ(dt,from_tz,to_tz)

CONVERT_TZ() converts a datetime value dt from the time zone given by from_tz to the time zone given by to_tz and returns the resulting value. Time zones are specified as described in Section 9.6, “MySQL Server Time Zone Support”. This function returns NULL if the arguments are invalid.

The current values of the global and client-specific time zones can be retrieved like this:

mysql> SELECT @@global.time_zone, @@session.time_zone;

The timezone values can be given in several formats, none of which are case sensitive:

• The value ‘SYSTEM’ indicates that the
  time zone should be the same as the
  system time zone.
• The value can be given as a string
  indicating an offset from UTC, such
  as ‘+10:00’ or ‘-6:00’.
• The value can be given as a named
  time zone, such as ‘Europe/Helsinki’,
  ‘US/Eastern’, or ‘MET’. Named time
  zones can be used only if the time
  zone information tables in the mysql
  database have been created and
  populated.

PS: Read about GMT vs UTC on About.com. GMT is the solar time at Greenwich, London while UTC] is a time standard based on International Atomic Time (TAI) with leap seconds added at irregular intervals to compensate for the Earth’s slowing rotation. Both are same if viewed as a time-zone.