How to build a TRIGGER in POSTGERSQL

Hi ,

I need some help in building trigger and information about sysdate
(System date), any help will be appreciate.

1) I need to build a trigger that every time I insert into the table
one of the columns will get +1 number.

I have it in ORACLE ( see below the create of the sequence and
the trigger) but how you can do it in PostGer SQL)

CREATE SEQUENCE AD_MNG_SYS_SEQ MINVALUE 1 MAXVALUE 999999 CYCLE;

CREATE TRIGGER AD_MNG_SYS_TRIG
BEFORE INSERT ON AD_MNG_SYS
REFERENCING OLD AS OLD NEW AS NEW FOR EACH ROW
BEGIN
Select AD_MNG_SYS_SEQ.NEXTVAL INTO :new.AMS_ID FROM Dual;
END;
/

2) what is equal to 'sysdate' (to get/put the system date in a
table) in PostGerSQL.

Thanks,

Ilan