Sql Server 2008 - Convert localized DateTime column to UTC

I have some columns in a few tables in my database that are all in the localized server DateTime values. I want to convert these all to UTC DateTime values (does not need to开发者_如何学Python be DateTime2 since it will be assumed the new values will be in UTC).

I would like to do this in a single SQL statement. I am not entirely sure how to perform this as I do not spend a lot of time in the database.

Assumptions can be made that my table name is TestTable and my localized DateTime column is called TestDateTime.

I would want the script to do the update to the table as well as the conversion.

Any way to possibly do this?

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You can substract getutcdate() from getdate() to find the difference:

select  DateAdd(s,DateDiff(s, getdate(),getutcdate()), LocalizedDateColumn)

This assumes you are in the same summertime/wintertime state as the time you're trying to convert. Not ideal, but the best conversion I know of that you can do in pure SQL.

A C# client has a much stronger conversion:

yourDateTime.ToUniversalTime()

Unlike the SQL version, the .NET version will correctly convert a wintertime date during the summer.