CREATE SEQUENCE customers_seq START WITH 1000 INCREMENT BY 1 NOCACHE NOCYCLE;

CREATE OR REPLACE TRIGGER JOB_INSTANCE_BRI BEFORE INSERT ON JOB_INSTANCE FOR EACH ROW BEGIN SELECT JOB_INSTANCE_SEQ.nextval INTO :new.JOBINSTANCEID FROM dual;
  END;

DROP SEQUENCE HIBERNATE_SEQUENCE;
CREATE SEQUENCE "HIBERNATE_SEQUENCE" INCREMENT BY 1 START WITH 1000 CACHE 100 NOORDER NOCYCLE;
select HIBERNATE_SEQUENCE.nextval from dual grant SELECT ON HIBERNATE_SEQUENCE to ROLE;

https://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_6015.htm

http://stackoverflow.com/questions/13782824/how-to-add-a-sequence-column-to-an-existing-table-with-records

http://stackoverflow.com/questions/11464396/add-a-auto-increment-primary-key-to-existing-table-in-oracle