How to relate the middle table with One or Many relationship? I am currently developing a simple CRM system. These are my tables: users, roles, role_users, customers. 



Rules:


A user can only be assign with a single role
A role can have a 1 or many users 
A Customer is assigned to a user 


Question: 
Did I mark the correct relationship in the screenshot above?
If a user can have no more than a single role, and this will ever change, then put role_id directly on the user table, then the relationship between role table and user table is a single role to many users.