Select distinct from the Users table

Hi;

RT-3.6.3 mysql mod_perl2

What is the best way to do “select distinct(Organization) from Users
Order by Organization” using the API

As far as I understand it $RT::Handle->FetchResult returns the first
value and one can only use FromSQL with the tickets table.Is there any
other hidden methods there I need to fish out.
I would use RT::Users and Limit if there is a quick way to do distinct
org, I have > 1 million rows in the users table and I am not too keen on
grabbing all rows and then sort for distinct.

Any help or pointers will be greatly appreciated.

Thanks;

Roy