find unindexed foreign key columns

I use the following query to find the unindexed columns.

column columns format a35 word_wrapped
column table_name format a35 word_wrapped
col a_column format a35 word_wrapped
col b_column format a35 word_wrapped
col status format a9 word_wrapped

select * from
(
select owner,decode( b.table_name, NULL, 'unindexed', 'ok' ) Status,
      a.table_name, a.columns a_column, b.columns b_column
from
( select a.owner,substr(a.table_name,1,30) table_name,
            substr(a.constraint_name,1,30) constraint_name,
        max(decode(position, 1,     substr(column_name,1,30),NULL)) ||
        max(decode(position, 2,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position, 3,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position, 4,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position, 5,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position, 6,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position, 7,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position, 8,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position, 9,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position,10,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position,11,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position,12,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position,13,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position,14,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position,15,', '||substr(column_name,1,30),NULL)) ||
        max(decode(position,16,', '||substr(column_name,1,30),NULL)) columns
    from dba_cons_columns a, dba_constraints b
   where a.constraint_name = b.constraint_name
     and b.constraint_type = 'R'
and a.owner <> 'SYSTEM' and b.owner <> 'SYSTEM'
   group by a.owner,substr(a.table_name,1,30), substr(a.constraint_name,1,30) ) a,
( select table_owner,substr(table_name,1,30) table_name, substr(index_name,1,30) index_name,
        max(decode(column_position, 1,     substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 2,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 3,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 4,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 5,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 6,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 7,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 8,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position, 9,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position,10,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position,11,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position,12,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position,13,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position,14,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position,15,', '||substr(column_name,1,30),NULL)) ||
        max(decode(column_position,16,', '||substr(column_name,1,30),NULL)) columns
    from dba_ind_columns
   group by table_owner,substr(table_name,1,30), substr(index_name,1,30) ) b
where a.table_name = b.table_name (+)
and a.owner=b.table_owner
  and b.columns (+) like a.columns || '%'
)
--where status <> 'ok'