Database Tips: Use UTC Time Fields for Your Time-based Data

If you are working with date time fields and care about business hours between 7am and 7pm (or slightly later) only, then regular date time fields with local time will be fine.

But if your clock runs 24 hours and/or 7 days a week, and you cover multiple time zones, or have daylight savings time, then you need to be careful. Real-world examples of such environments include air travel, factory processing, and energy billing.

You will need two date time fields in your database. One with the local time, and one with the time in UTC (Universal Time Coordinates).

UTC is what we used to call Greenwich Mean Time (GMT). There are two hours a year when you cannot do accurate time variance calculations using local time only. These are the hours when daylight savings moves forward and back--they will make these calculations wrong. You need an equivalent period without the daylight savings component. UTC is the solution to this.

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