Create Sequence/Trigger in Oracle

Use the following script

DROP SEQUENCE SEQNAME;

CREATE SEQUENCE SEQNAME
START WITH 1
MAXVALUE 9999999999
MINVALUE 1
NOCYCLE
NOCACHE
NOORDER;

CREATE OR REPLACE TRIGGER TRIGGERNAME
BEFORE INSERT
ON TABLENAME
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
BEGIN
SELECT SEQNAME.NEXTVAL
INTO :NEW.PRIMARYKEYNAME
FROM DUAL;

EXCEPTION
WHEN OTHERS THEN
RAISE_APPLICATION_ERROR('-20000','TRIGGERNAME');
END;
/

Greetz,

G