Dates and Times in Databases
The place to start is the timekeeping system: how the passage of time is measured. Within a day, the system is rather standardized, with 24-hour days divided into 60 minutes and each minute divided into 60 seconds. The big issue is the time zone, and even that has international standards.
For dates, the Gregorian calendar is the calendar prevalent in most of the developed world. February follows January, school starts in August or September, and pumpkins are ripe at the end of October (in much of the Northern Hemisphere at least). Leap years occur just about every four years by adding an extra day to the miniature winter month of February. This calendar has been somewhat standard in Europe for several centuries. But it is not the only calendar around.
Over the course of millennia, humans have developed thousands of calendars based on the monthly cycles of the moon, the yearly cycles of the sun, cycles of the planet Venus (courtesy of the Mayans), logic, mere...