Oracle 18c

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create table mail_address_entries (
    pk_serial_no number, addrno number, address varchar2(5) unique,
    constraint pk_mail_address_entries primary key (pk_serial_no, addrno)
)
/
create or replace view mail_address_book as
    select a.pk_serial_no, a.address address_a, b.address address_b
    from mail_address_entries a  
    join mail_address_entries b on (
        b.pk_serial_no = a.pk_serial_no and a.addrno = 1 and b.addrno = 2 
    );
create or replace trigger trig_mail_address_book
instead of insert on mail_address_book
begin
    if inserting then -- the same for updating, deleting 
        insert into mail_address_entries values (:new.pk_serial_no, 1, :new.address_a);
        insert into mail_address_entries values (:new.pk_serial_no, 2, :new.address_b);
    end if;
end;
/
begin  dbms_errlog.create_error_log (dml_table_name => 'mail_address_book'); end;
/
1 rows affected

create or replace type addrRow force is object (pk_serial_no number, address_a varchar2(5), address_b varchar2(5));
create or replace type addrRows is table of addrRow;
declare
    changed number := 0;
    testdata addrRows; 
begin
    testdata := addrRows (
        addrRow (1, 'A', 'B'),
        addrRow (2, 'B', 'A'),
        addrRow (3, 'C', 'A'),
        addrRow (4, 'C', 'C'),
        addrRow (5, 'C', null),
        addrRow (6, null, null),
        addrRow (7, 'D', 'E'),
        addrRow (8, 'E', 'F')
    ); 
    for r in (select * from table (testdata)) loop 
        begin
            insert into mail_address_book values (r.pk_serial_no, r.address_a, r.address_b);
            changed := changed + 1;
        exception when dup_val_on_index then 
            insert into err$_mail_address_book (pk_serial_no, address_a, address_b, ora_err_mesg$)
            values (r.pk_serial_no, r.address_a, r.address_b, 'error'); 
        end;
    end loop;
end;
/
1 rows affected

select to_char (pk_serial_no) no, address_a a, address_b b, 'ok' msg 
from mail_address_book 
union all
select pk_serial_no, address_a, address_b, ora_err_mesg$ msg 
from err$_mail_address_book
order by 1
;


NO
A
B
MSG


1
A
B
ok

2
B
A
error

3
C
A
error

4
C
C
error

5
C
null
ok

6
null
null
ok

7
D
E
ok

8
E
F
error
NO	A	B	MSG
1	A	B	ok
2	B	A	error
3	C	A	error
4	C	C	error
5	C	null	ok
6	null	null	ok
7	D	E	ok
8	E	F	error