Oracle PL/SQL | Question

Question
Input Data:
Col1 col2 col3
1 2 1
1 2 2
1 2 3
2 3 7
2 3 8
2 3 9

Output Data
1 2 1,2,3
2 3 7,8,9
Answer:
create table table01 as
with table02 as(
select '1' field01, '2' field02, '1' field03 from dual union
select '1' field01, '2' field02, '2' field03 from dual union
select '1' field01, '2' field02, '3' field03 from dual union
select '2' field01, '3' field02, '7' field03 from dual union
select '2' field01, '3' field02, '8' field03 from dual union
select '2' field01, '3' field02, '9' field03 from dual
)select * from table02;

select distinct field01 || field02 || wmsys.wm_concat(field03) over( partition by field01 || field02 order by field01 || field02) field01 from table01

drop table table01