SELECT u.username USERNAME, u.full_name FULL_NAME, u.email_address EMAIL, u.end_date END_DATE, sg.security_group_name SECURITY_GROUP
from knta_security_groups_nls sg, knta_user_security us, knta_users u
 where u.user_id = us.user_id and sg.security_group_id = us.security_group_id
 order by u.last_name, u.first_name

Note that this will also include disabled Security Groups.

SELECT u.username USERNAME, u.full_name FULL_NAME, u.email_address EMAIL, u.end_date END_DATE, sg.security_group_name SECURITY_GROUP
from knta_security_groups_nls sg, knta_user_security us, knta_users u
 where u.user_id = us.user_id and sg.security_group_id = us.security_group_id
 order by u.last_name, u.first_name

Note that this will also include disabled Security Groups.

Thank you so much Etienne!