Dave Mason looks at DDL triggers:
DDL triggers and the events they handle are run within the same transaction, which can be rolled back. This is a powerful and convenient feature. It gives you the ability to programmatically “undo” undesirable events. Let’s look at a variation of the previous DROP_TABLE trigger we created. This script will create a temporary logging table, drop the previous trigger, and create it again. This time, the trigger will roll back the transaction, preventing the table from being dropped. Then it inserts a message to the log table.
There are a few gotchas here, to be sure, but DDL triggers are powerful tools.