select b1.owner, b1.table_name, b1.constraint_name, c1.column_name, c1.position, 
       b1.constraint_name, b1.delete_rule 
  from all_constraints b1, all_cons_columns c1 
 where c1.table_name = :tabname
   and c1.owner = :ownname
   and b1.r_owner = c1.owner
   and b1.r_constraint_name = c1.constraint_name
   and b1.constraint_type = 'R' 
 order by b1.owner, b1.table_name, b1.constraint_name, c1.position;