SQL to find unindexed Ref key

select decode( b.table_name, NULL, '****', 'ok' ) Status, 
a.table_name, a.columns, b.columns
from 
( select 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 user_cons_columns a, user_constraints b
where a.constraint_name = b.constraint_name
and a.table_name in ('OT_INVOICE_HEAD')
and b.constraint_type = 'R'
group by substr(a.table_name,1,30), substr(a.constraint_name,1,30) ) a, 
( select 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 user_ind_columns 
group by substr(table_name,1,30), substr(index_name,1,30) ) b
where a.table_name = b.table_name (+)
and b.columns (+) like a.columns || '%'
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