External database authentication
From MoodleDocs
This method uses an external database table to check whether a given username and password is valid. If the account is a new one, then information from other fields may also be copied across into Moodle.
This is done by mapping fields at the bottom of the database authentication page. Each data field in the user profile has a text field next to it. Enter the name of the column in the external database that maps to the profile data field.
See also
- Using Moodle Special and characters con tilde (accute accent) when connected to external database forum discussion
- Using Moodle HELP!--User Authentication problem forum discussion