Designing User & its Sub User Database Diagram Problem There are some business category e.g. Travel Agency, Hotel, Car Rental etc.
Roles:


Management rolesSuper Admin, Staff
Customer side roles are Owner, admin and sales counter
May be etc. customer side roles will be added


Status i.e. On-Hold, Active, In-Active, Blocked, Deleted etc.
Scenario:


Each user in the database has its role and status with other credentials
Super Admin or Staff creates a customer (USER) with category e.g. &quot;Travel Agency&quot; and provide owner details
Now this Travel Agency (USER) has its own SUB_USERS that may be one or many

Now I am confused between user and sub users. 
The work that I done so far is as following in shape of ERD:

Please put me on the right path as to how can I create a USER with its SUB USERS?
Thanks in anticipation
Why not just get rid of the main_user and sub_user tables and have a nullable field on the users table called parent_user_id. Then you can use a self-join on users.parent_user_id = users.user_id to get all the sub-users for a given Travel Agency. (When the parent_user_id field is null, that's a Travel Agency.)