I just went to the Palo Alto Court office and asked them to give me a letter to indicate that I had no outstanding tickets for immigration purposes and that I had successfully completed traffic school for the ticket that I got. They had it ready for me within 2 weeks. That letter also indicated that I had successfully completed traffic school for the specific case # and that it has been dismissed and closed. Just let them have a copy of your driving ticket information that has the case number. If you don't have the case number, you'll be stuck going through books and books of micro-fiches!
Not certain if this is specific to the county, so different counties might have different policies.
The letter went something like:
A search of the traffic index was conducted for <my name>, date of birth <dob>, DL <license number>. We have found that the defendent has successfully completed traffic school for case #<case number> and the case is now dismissed and closed. There are no other records for any other tickets in Santa Clara County.
-Senthil.