I am developing a document management system where i have multiple brnaches, departments and sub-departments. I want to give permissions(view, update and delete) to each sub-department. Here sub-department will have multiple documents. A user can have access to multiple departments and its sub-departments. If a user have access to department and its sub-department then he must be able to access all documents under it(with given permissions). How to do it in node-express and mysql.

Note – User can have multiple permission for each sub-department.

I am not able to design table for role_permissions and UI as well. And also how to manage permission on user-level.