I don't rely on time calculations at the database level. I handle them in the application based on UTC time stored in the database and the user's time zone. This shifts the problem to the application code, where I can control it precisely and make conscious decisions about how to handle specific business requirements, such as when a day ends or how to deal with events across different time zones. It also makes it possible to properly test all cases with unit tests.
This is the only way. To do otherwise smacks of poor programming practice and is very often a sign the coder doesn't habitually consider the world outside their own timezone.
It only works backwards (though you can probably get away with it if your future dates are not too far forward). There are ~10 tzdb updates a year due to rule changes and if you bake a date on the other side of one to UTC too early then your app is going to have incorrect datetimes
beybol · · focus · HN ↗
GJim · · focus · HN ↗
Macha · · focus · HN ↗