Tutorial : using foreign keys, retrictions etc

Hi,

I've decided to switch from mysql to postgresql as my database server. I
do mostly web programming (who doesnt these days?) with more than a 100
sites developed (using mysql).

I've read about postgresql and it's features (such as triggers, stored
procedures, views) and I'd like to know if there is some tutorial/snippet
of code regarding such features specially the use of foreign keys and
referetial integrity.

To give a more concrete example the next app I'd like to use postgresql
needs this behaviour :

table A
id, name

table B
id, foo

table C
id, date

If I change id in table A update table B to change it too (I think it's
called cascade).

Thanks.

- RM