I am having a project which will have country dropdown at the top to select counrties. For example usa,india and hongkong. Depends on the country selection serveral featuers will be enabled or disabled.
In project I am having base country by default for example india. So whenever any user will come. I want to store its login datetime as per indian standard time regardless user is from hongkong,usa or india. My webserver is hosted in USA.
Is that possible? Can any one have any idea for that.
If you save your time in unixtime, you can have a field in the user table called offset. Where it's value is how much the system needs to offset the time.
Then you'd just fetch that variable and save that as a session value or something similar. And use that to offset the datetime in the system.
For example. Hong Kong is +8 hours from GMT. Now in GMT Unixtime is: 1242293400 (9:30 am). 8 hours is 28800 seconds. You would then store this value in your server. So the time would be 1242322200 (5:30 pm same day)
IF you are using SQL Server 2008, look at the new datetime datatypes which allow you to store the offset/timezone as well.
What you want to do is store any datetime value as UTC. Which means storing as a time zone independent value.
You can either set some sort of insert trigger in your MS-SQL server (I assume you use MS-SQL because of the asp.net part). There you determine the UTC time like this.
`-- MS SQL (use instead of GETDATE())
DECLARE @currentTime datetime
SET @currentTime = GETUTCDATE()`
If you want to do it in code just use UtcTimeNow to access the UTC time.
// C# (use instead of DateTime.Now)
DateTime currentTime = DateTime.UtcNow;
If you want you can always convert the UTC time to any given local time. By using the TimeZoneInfo class.
That way you have the right time in your database (UTC) and can convert it to the appropriate time for the User.
The most important part when dealing with times and timezones is to store it as UTC. That way it's can be transported and compared easily.