![]() Warning! UTC has leap seconds, these look like ' 23:59:60' and canīe added randomly, with 6 months prior notice, due to the slowing of Timestamp, but it will select a different datetime from MySQL Timezone CheatsheetĬhanging the timezone will not change the stored datetime or ![]() Here are some notes I collected of how to work with timezones as a form of cheatsheet for myself and others which might influence what timezone the person will choose for his/her server and how he/she will store date and time. On the other hand if you have control of the timezones of the servers you work with then you can have everything set to UTC internally and never worry about timezones and DST, at least when it comes to storing internal time. Provided that DST is not in effect, most time zones may be written in short form as UTC +/-n (or GMT+/-n), such as Melbourne Australia, UTC+10, and Los Angeles, California, U.S.A., UTC-8.It seems that it does not matter what timezone is on the server as long as you have the time set right for the current timezone, know the timezone of the datetime columns that you store, and are aware of the issues with daylight savings time. There are a total of 24 standard time zones in the world, when the full hour difference is taken into account. On the other hand, one that more people are familiar with, a time zone is a representation of a region with a common, ever consistent local time, despite seasonal fluctuations of the offset. The first meaning of time zone is a uniform representation of a particular region, where the time is determined offset from a global reference (usually UTC). Time Zones are typically defined by two variations. Some time zones are irregularly-shaped, due to establishment of political boundaries, and seasonal time changes (DST or Daylight Saving Time). There are exceptions, however, for the benefit of those with geographical and political issues. Standard time zones are geometrically defined by the subdivision of the Earth's sphere into 24 lunes (wedge shaped sections), surrounded by meridians that are 15 degrees of longitude apart from each other, hence the general rule of one-hour time differences between neighbouring regions. However, in 1972, a new system was discovered, and this system involved the use of leap seconds.Īs a general rule, adjacent time zones are exactly one hour apart. Knowing this, atomic clocks were changed annually to closely match GMT. The Earth's rotation is not constant, and time is ideally, a constant thing, wherever a person is in the earth. However, the flaw lies in how the mean solar time is determined by the rotation of the Earth. Solar-based time has been used all throughout the history of time-keeping, of which the best-known is the sundial. GMT, on the other hand, is the mean solar time at the 0 degree longitude (known as the Prime Meridian). It also has leap seconds (time particle that measures time not on the passage of seconds, but on the Earth's angular rotation) that are announced at irregular intervals for the compensation of geographical occurrences, such as the earth's slowing rotation. UTC has standard seconds as defined by the International Atomic Time. ![]() UTC is a high precision atomic time standard, which measures time by the nanosecond. UTC replaced GMT (Greenwich Mean Time) in 1972 as the time standard. Conventionally, people compute their local time as an offset from UTC (Coordinated Universal Time). Time Zones are regions on Earth that use the same local time.
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