CODEWITHSUNDEEP
c#sql-serverdatetimeutc
Pbirkoff
Pbirkoff

Reputation: 4702

How to store my dates?

I don't have much experience with Utc Dates, but from what I know, they are in most cases the best way to store dates.

But I'm currently working on a program and I'm in doubt what will be the best way to store my dates. In the program, a user can follow a course for five weeks, starting on the day of registration. Every day he has to fill in a form, which is saved for that day.

Currently, I'm saving the StartDate and EndDate of the course as DateTime (no Utc) Should I save this as Utc, or isn't it necessary? Because I only need the day (if the user registers on February 8th at 10:04, all the system needs to know is that February 8th is the first day of the course. Is there maybe a better way to store this information? And what would be the best way to save system-event-dates (like user logged in, account created, etc)?

I used to store the form-data also with a DateTime, to calculate on which day it was submitted, but I changed it so it only saves the relative day-number (e.g. day 5).

Btw, I'm using C# and a SQL Server database.

Upvotes: 3

Views: 6389

Answers (3)

Alexey Raga
Alexey Raga

Reputation: 7545

Generally you want to store in UTC if there is a functional requirement for your system to be able to work with users in different timezones.

Let's say you have a user in Hong Kong and a user in Sydney looking at the same event. If you want them both see the event date (and time) in their timezones, then here we are, you will probably need to store it in UTC and then present to users respecting their geo locations.

If you don't have such requirements, you don't do such conversions and you only assume one timezone then you don't need to add more complexity into your system, just use Date column and store the current date there.

But if you do - go for UTC. In this scenario you will need DateTime, not just Date. This is because 21:30 in one timezone can be 2:30 next day in another timezone so time really matters.

When showing to a user you may convert it to the user's timezone and then throw time away, but in order to make the conversion correct you will need to keep time.

It is easy to work with UTC in .NET, DateTime has .ToUniversalTime() method that converts a datetime value to UTC for you:

var utcNow = DateTime.Now.ToUniversalTime();

there is also a property:

var utcNow = DateTime.UtcNow;

EDITED

Use TimeZoneInfo static class to convert datetimes from/to timezones you need (for example from UTC to the specified user's timezone:

TimeZoneInfo.ConvertTimeToUtc(...)
TimeZoneInfo.ConvertTimeFromUtc(...)

Upvotes: 1

Eoin Campbell
Eoin Campbell

Reputation: 44306

UTC (Coordinated Universal Time) has to do with the time component of a date. It's a standard way to store DateTimes so that you can compare without worrying about timezones.

If all you are worried about is the Date Component & Timezone/Location is unimportant you could just store it in the database as 2012-02-01 00:00:00

You can get the date only component in .NET using

System.DateTime.Today;

Alternatively if you're working with some other Date...

DateTime dt = DateTime.Now;
dt.Date; // <--- this will give the Date Component with the Time stripped back to 00:00:00

Upvotes: 3

zmbq
zmbq

Reputation: 39059

Why don't you just store the dates in a DATE database column, and not worry about time zones at all?

Upvotes: 1

Related Questions