Si desea fld_id
para ser un valor secuencial, deberá crear una secuencia y un disparador
CREATE SEQUENCE sequence_name
START WITH 1
INCREMENT BY 1
CACHE 20;
CREATE OR REPLACE TRIGGER trigger_name
BEFORE INSERT ON table_name
FOR EACH ROW
BEGIN
SELECT sequence_name.nextval
INTO :new.fld_id
FROM dual;
:new.fld_date := (SYSDATE - date '1970-01-01') * 60 * 60 * 24;
END;