 timezone handling creating a timezone form item using date api this is simple just use the datetimezone type which is provided by dateapimodule php form timezone array type datetimezone defaultvalue timezone description select a timezone if all the events will happen in the same place select that place s timezone  converting to and from utc in the new system you just need to know the timezone name and either the utc or local time we store the utc time and the timezone name in the database in two separate fields we retrieve that data and do php date the utc value from the database localzone the name of the local timezone type the type of date value datedatetime dateiso or dateunix date datemakedate date utc type datetimezoneset date timezoneopen localzone date now contains the local value of the date output it like print dateformatdate date custom m d y h i to convert a local date back to utc to store it in the database do php date local date value localzone the name of the local timezone type the type of date value datedatetime dateiso or dateunix date datemakedate date localzone type datetimezoneset date timezoneopen utc date now contains the utc value of the date output it like print dateformatdate date custom m d y h i  use of timezone abbreviations the api doesn t handle timezone abbreviations at all there s no way to do it right because they are not unique est could be eastern standard time or european summer time we need the full undeprecated timezone name which looks like america chicago it is comprised of the name of the continent and the major city in the timezone older names like us central are deprecated because the area names change but city names rarely do some good info about timezones is at http enwikipediaorg wiki zoneinfo also we do not use spaces in the timezone names so we use america newyork not america new york the php 52 date functions and mysql native timezone handling all expect names without spaces in them to work correctly you can use the php function timezonenamefromabbr  to try to translate to and from abbreviations but it s not entirely reliable as noted above if we have the current offset and we know if it s currently daylight savings time or not you can combine that with the abbreviation to get the timezone name but that s a lot of if s timezone names the complete list of allowed undeprecated timezone names is africa algiers africa asmera africa bangui africa blantyre africa brazzaville africa bujumbura africa cairo africa ceuta africa daressalaam africa djibouti africa douala africa gaborone africa harare africa johannesburg africa kampala africa khartoum africa kigali africa kinshasa africa lagos africa libreville africa luanda africa lubumbashi africa lusaka africa malabo africa maputo africa maseru africa mbabane africa mogadishu africa nairobi africa ndjamena africa niamey africa portonovo africa tripoli africa tunis africa windhoek america adak america anchorage america anguilla america antigua america araguaina america aruba america asuncion america atka america barbados america belem america belize america boavista america bogota america boise america buenosaires america cambridgebay america cancun america caracas america catamarca america cayenne america cayman america chicago america chihuahua america cordoba america costarica america cuiaba america curacao america dawson america dawsoncreek america denver america detroit america dominica america edmonton america eirunepe america elsalvador america ensenada america fortwayne america fortaleza america glacebay america godthab america goosebay america grandturk america grenada america guadeloupe america guatemala america guayaquil america guyana america halifax america havana america hermosillo america indiana indianapolis america indiana knox america indiana marengo america indiana vevay america indianapolis america inuvik america iqaluit america jamaica america jujuy america juneau america kentucky louisville america kentucky monticello america knoxin america lapaz america lima america losangeles america louisville america maceio america managua america manaus america martinique america mazatlan america mendoza america menominee america merida america mexicocity america miquelon america monterrey america montevideo america montreal america montserrat america nassau america newyork america nipigon america nome america noronha america panama america pangnirtung america paramaribo america phoenix america portauprince america portofspain america portoacre america portovelho america puertorico america rainyriver america rankininlet america recife america regina america riobranco america rosario america santiago america santodomingo america saopaulo america scoresbysund america shiprock america stjohns america stkitts america stlucia america stthomas america stvincent america swiftcurrent america tegucigalpa america thule america thunderbay america tijuana america tortola america vancouver america virgin america 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