Event recurrence - in database or in application code ????

One of the features that I am attempting to implement in the system that I
am building is
the capability to schedule events (with recurrence). My question to those of
you that are
more experienced in postgresql is whether you would implement this
functionality in the
database level using triggers or at the application code level (PHP).

Ideally I would like to be able to generate an event off a template
appointment (initial appt)
and have it schedule identical appointments hourly, daily, weekly, monthly,
or by selectable
range (ie: first tuesday every month). I would also like to have the
capability to remove an
appointment and leave others (much like using C pointers - I think)or to
remove all
(cascading delete).

Any suggestions, etc gratefully appreciated.

Darrin