How to calculate the local datetime from a utc datetime in tsql (sql 2005)?

Question

i want to loop over a period of time in tsql, and print the utc datetimes and our local variant. We live in UTC +1, so i could easily add 1 hour, but in the summertime we live i

Answer 1

Assuming you are using SQL 2005 upwards, you can develop a SQL CLR function to take a UTC date and convert to the local date.

This link is an MSDN How-To explaining how you can create a scalar UDF in C#.

Create a SQL function along the lines of

[SqlFunction()]
public static SqlDateTime ConvertUtcToLocal(SqlDateTime utcDate) 
{
    // over to you to convert SqlDateTime to DateTime, specify Kind
    // as UTC, convert to local time, and convert back to SqlDateTime
}

Your sample above would then become

set @localdate = dbo.ConvertUtcToLocal(@utcdate)

SQL CLR has its overheads in terms of deployment, but I feel cases like this are where it fits in best.