Time zone conversion

Here is a workaround for importing time data from servers that do not observe daylight saving time (DST), to a server that does.

1. Ensure MySQL time zone tables are loaded.

2. Collect the source timestamp with gmmktime(), offset by the local number of hours from UTC:

$timestamp = gmmktime($hours + $localHrsFromUTC, $minutes, $seconds, $month, $day, $year, $isDaylight);

3. Retrieve with:

SELECT CONVERT_TZ(FROM_UNIXTIME(timestamp-28800), 'LOCAL TIMEZONE NAME','UTC') 
FROM tableName;

Without CONVERT_TZ, FROM_UNIXTIME() converts the UTC timestamp to the server's timezone, which ignores DST.

Last updated 9 Apr 2022

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