Case-insentive search

We are trying to perform a case-insensitive search on a specific column of a table, e.g.

select cust_name from customer
  where upper(street_address) like upper('pattern%');

Both street_address and pattern are in mixed case. But we also want to be able to use the index on street_address. Is this possible ? Any suggestions or comments will be greatly appreciated.

• Aziz Rahman