Trigger / rule question

Hi,

Are a trigger or rule part of a query, that is:

1. Does an insert, update or delete statement return before or after an
"After" trigger (is such a trigger or rule synchronous or a-synchronous?
2. Is there a concept of a rule or trigger that fails? If so, if a
trigger or rule fails, does the insert, update or delete statement
(transaction)  fail? 

TIA

-- 
Groeten,

Joost Kraaijeveld
Askesis B.V.
Molukkenstraat 14
6524NB Nijmegen
tel: 024-3888063 / 06-51855277
fax: 024-3608416
e-mail: J.Kraaijeveld@Askesis.nl
web: www.askesis.nl