Time in practice.
WHAT TO SET
The application's time zone explicitly.
WHAT TO STORE
A consistent standard, converting at display.
WHY
Storing local times without zone information cannot be resolved later.
WHAT TO CONSIDER
Whether all your users are in one zone.
For a business serving one country, that simplifies matters considerably.
WHAT TO DO IF THEY ARE NOT
Store a zone per user, and convert for each.
WHAT TO BE CAREFUL WITH
Scheduled tasks, which run in the server's zone Date boundaries, where a day differs between zones Comparisons between values in different zones
THE DATE BOUNDARY POINT
A report covering today means different periods in different zones.
Define which zone a report uses, and state it.
WHAT TO DISPLAY
Times with a clear indication of the zone, where ambiguity exists.
WHAT TO TEST
Behaviour around midnight Scheduled tasks running at the intended local time
