while waiting that guid-field, I added two functions:

while waiting that guid-field, I added two functions:

auth_get_users ()
        Returns all userobjects from external database, with userinformation
        like address, phone ...

auth_sync_users ()
        1. Adds users from externaldatabase to moodle.
        2. renamed user in moodles db if renamed in externaldb
        3. "Delete" user in moodles db if removed from externaldb

and configuration interface for guid. ;)