PLS-00049: bad bind variable Triggers - oracle

Question

I'm trying to make this trigger work. What it does is, this will execute before deleting data from a table and its affiliated table, then insert that deleted data into 2 tables (which I named into tb1_arch and tb2_arch). I've been searching possible fixes in google but I really have no idea how to make this work
CREATE OR REPLACE TRIGGER trig
BEFORE DELETE ON tb1 FOR EACH ROW
FETCH
INSERT INTO tb1_arch VALUES (:old.OrderNum, :old.tb1Date,:old.CustomerName);
DBMS_OUTPUT.PUT_LINE('Data archived.');
END;
the trigger was created above. but when I added this line
INSERT INTO tb2_arch VALUES (:old.OrderNum, :old.ItemNum, :old.Pieces);
after INSERT INTO tb1_arch VALUES, it gives me an error
"Error at line 5: PLS-00049: bad bind variable 'OLD.PIECES'"
Any help would be appreciated!
EDIT: as Mr. Vijayakumar suggested, I did the following:
CREATE OR REPLACE TRIGGER trig
BEFORE DELETE ON tb1
REFERENCING OLD AS old FOR EACH ROW
INSERT INTO tb1_arch VALUES (:old.OrderNum, :old.tb1Date,:old.CustomerName);
INSERT INTO tb2_arch VALUES (:old.OrderNum, :old.ItemNum, :old.Pieces);
DBMS_OUTPUT.PUT_LINE('Data archived.');
END
However, I'm still having the same error.
EDIT: removed FETCH, I'm still encountering the same problem
CREATE OR REPLACE TRIGGER trig
BEFORE DELETE ON tb1 FOR EACH ROW
INSERT INTO tb1_arch VALUES (:old.OrderNum, :old.tb1Date,:old.CustomerName);
INSERT INTO tb2_arch VALUES (:old.OrderNum, :old.ItemNum, :old.Pieces);
DBMS_OUTPUT.PUT_LINE('Data archived.');
END;
The table are as follows:
tb1:
create table tb1 (
OrderNum integer NOT NULL primary key,
tb1Date date NOT NULL,
CustomerName varchar2(50) NOT NULL,
--constraints
CONSTRAINT tb1_uc unique (CustomerName)
);
tb2
create table tb2 (
OrderNum integer NOT NULL,
ItemNum integer NOT NULL,
Pieces integer NOT NULL,
--constraints
CONSTRAINT tb2_fk foreign key (OrderNum) references tb1(OrderNum),
);

Answer 1

The keyword FETCH should be causing this, replace it by BEGIN, which is the right syntax,
CREATE OR REPLACE TRIGGER trig
BEFORE DELETE ON tb1 FOR EACH ROW
BEGIN
INSERT INTO tb1 VALUES (:old.OrderNum, :old.Date,:old.CustomerName);
INSERT INTO tb2_arch VALUES (:old.OrderNum, :old.ItemNum, :old.Pieces);
DBMS_OUTPUT.PUT_LINE('Data archived.');
END;
EDIT: The column name you refer using OLD might be invalid, which is the reason for this error.
Trigger will be applicable for only ONE Table's INSERT/UPDATE/DELETE event. Though, you can refer multiple tables in the body.
But OLD and NEW will be always referring the table you mentioned in DDL like DELETE ON tb1.
The below modified code will help you.
CREATE OR REPLACE TRIGGER trig
BEFORE DELETE ON tb1 FOR EACH ROW
DECLARE
v_ItemNum tb2.ItemNum%TYPE;
v_Pieces tb2.Pieces%TYPE;
BEGIN
INSERT INTO tb1_arch VALUES (:old.OrderNum, :old.Date,:old.CustomerName);
/* Select the values for this item from table 2 */
SELECT ItemNum,Pieces
INTO v_ItemNum,v_Pieces
FROM tb2
WHERE OrderNum = :old.OrderNum;
/* Insert the selected values in the table2's archive version */
INSERT INTO tb2_arch VALUES (:old.OrderNum, v_ItemNum, v_Pieces);
/* Delete the entry */
DELETE from tb2 WHERE OrderNum = :old.OrderNum;
DBMS_OUTPUT.PUT_LINE('Data archived.');
END;
Alternatively, you can have another trigger for delete on table2 and archive the data there.