Reminder of issue 354: http://code.google.com/p/web2py/issues/detail?id=354
I have never used a select trigger, so I only have vague ideas about how it would be useful. For inserts, a single line is sufficient. For deletes/update, that is not true. You can look at (todor's fixes to) my implementation to see what a useful multi-record update/delete wrapper looks like. I used it for auditing. todor used it to make "hard deletes" into "soft deletes" (set a "deleted" mark on the record instead of really deleting it). "before" / "after" triggers are not a good solution in the sense that they may need to wrap/modify the actual call, rather than just happen before and after it. "multi tenancy" is a an example of what could be implemented with triggers (if it wasn't already built-in): add another condition to select/delete/update; another field to insert.
