Question

UPDATE

I am dealing with a legacy database where the datetime values have been stored in a specific timezone (not UTC). Assume it is not possible to change how we are storing these values.

END UPDATE

Say I have a SQL Server 2005 database with a table as follows:

[id] (int) not null   
[create_date] (datetime) not null

Suppose my [create_date] has been stored, by convention, as timezone TZ-A.

Suppose I want to retrieve this value (using SqlClient) from the database and display it in another timezone, TZ-B.

How do I do this?

DateTime from_db = // retrieve datetime from database, in timezone TZ-A
DateTime to_display = //convert from_db to another timezone, TZ-B

Answer 1

Use TimeZoneInfo

TimeZoneInfo timeZone1 = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");
TimeZoneInfo timeZone2 = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");
DateTime to_display= TimeZoneInfo.ConvertTime(from_db, timeZone1, timeZone2);

I also agree that storing in UTC is the way to go. The only downside is trying to explain UTC to users who want to write their own reports.