In order to review permissions, we want a list that contains what type of roles are assigned to which user. How can this be collected from the database?
The security groups are held in t_security_groups, with the security_group_id mapping to user_group_id via the t_security_group_members table, and then t_user_group_members will allow you to map that user_group_id to list of user_id values. Finally, t_users will tell you the user_name for a given user_id. However, depending on your exact needs here, you might be more interested in user_group_name, or indeed security_group_name.