how-to create a generic autoincrement id trigger in oracle

--CREATE A SEQUENCE

CREATE SEQUENCE  "SEQ_TBL_NAME"  

MINVALUE 1 MAXVALUE 999999999999999999999999999 

INCREMENT BY 1 START WITH 1 

CACHE 20 NOORDER  NOCYCLE ;

-- CREATE  THE TRIGGER 

CREATE OR REPLACE TRIGGER "TRG_TBL_NAME" 

BEFORE INSERT ON "TBL_NAME"

REFERENCING NEW AS New OLD AS Old

FOR EACH ROW

   DECLARE

   tmpVar NUMBER;

BEGIN

   tmpVar := 0;

   SELECT SEQ_TBL_NAME.NEXTVAL INTO tmpVar FROM dual;

   :NEW.TBL_NAME_ID:= tmpVar;

END TRG_TBL_NAME; 

/

ALTER TRIGGER "TRG_TBL_NAME" ENABLE;

COMMIT ;