SQL> with 
  2    t as ( 
  3     select 'abc,efg,ijk' a from dual
  4     union all
  5     select '12,45,78' from dual
  6    ),
  7    data as ( select ','||a||',' val, rownum coln from t ),
  8    split as (
  9      select substr(regexp_substr(val, ',[^,]*', 1, column_value),2) item, 
 10             column_value rown, coln
 11      from data,
 12           table(cast(multiset(select level from dual 
 13                               connect by level <
 14                                          length(val)-length(replace(val,',','')))
 15                      as sys.odciNumberList))
 16    )
 17  select max(decode(coln,1,item)) col1,
 18         max(decode(coln,2,item)) col2
 19  from split
 20  group by rown
 21  order by rown
 22  /
COL1         COL2
------------ ------------
abc          12
efg          45
ijk          78

3 rows selected.