Oracle Sequentietrigger maken

Probeer dit:

CREATE OR REPLACE TRIGGER TRIGGER1
BEFORE INSERT ON ACCOUNTS
FOR EACH ROW
  WHEN (new.ID IS NULL)
BEGIN
  :new.ID := ACCOUNTS_SEQ.NEXTVAL;
END;
/

Uw reeks zou er als volgt uit moeten zien:

CREATE SEQUENCE ACCOUNTS_SEQ 
  START WITH 1 
  INCREMENT BY 1;