select db_id(),db_name()

From BOL:

Effect of ANSI_WARNINGS Setting

The ANSI_WARNINGS setting affect query processor behavior despite the current settings of ARITHABORT and ARITHIGNORE.

For example, even if SET ARITHABORT or SET ARITHIGNORE is OFF, if...

Just wanted to clarify one thing:

The transaction is not rolled back unless you have xact_abort also set to ON. Only the statement that caused the error is rolled back.

To...

What is the compatibility level of your database? Should be 80 for functions to work.

You could use something like this:

if (select min(dbid) from master..sysprocesses where spid=@@spid)=<your production database id here>

xp_sendmail ...

Make sure SET ANSI_NULLS ON is in a separate batch.

ALTER DATABASE 'database'

SET SINGLE_USER WITH ROLLBACK IMMEDIATE

I think this is supposed to kill all connections. Am I wrong?

Why not use SET ANSI_NULLS ON?