Oracle SQL Techniques

Oracle SQL has the most features and flexibility of all of the implementation.
Oracle RDMS and SQL features usually appear downsteam in othe databases.

Functional Indices.

See http://www.akadia.com/services/ora_function_based_index_2.html

Firstly create a function:

create or replace function matterl0(matter_id in varchar2) return varchar2
deterministic
as
begin
  return '0'||matter_id;
end;
/

Then you can use this or any built in function in an index.