Trigger to update a record to null whenever there is an insert or update on a row in the table in Oracle DB

Question

Need help in writting a Trigger to update a record to NULL whenever there is an insert or update on a row in the table in Oracle DB.

CODE

create or replace trigger updateRowToNull
AFTER
UPDATE OR INSERT
ON CUSTOMER for each row
BEGIN
update customer set customeraddr=NULL;
END;

Answer 1

A trigger cannot modify the table to which it is attached with a separate transaction. A "before" trigger can, however, manipulate column values within the transaction that causes it to be fired.

create or replace trigger update_row_to_null
before update or insert on customer
for each row
begin
   :new.customeraddr := null;
end;