I'm designing a database for a new project and I'm looking for some feedback on the design before I start to implement. It basically consists of secure messaging system with those abilities :
- One user can send a message to one or many users
- Messages can be sent both to registered and unregistred users
- User can be a person or a company
- A company can have multiple user but only one administrator
1°) I am having difficulties with choosing how to approach the relashionship between Messages and User and particularly how to manage unregistred users.
2°) Is the relationship between User and userGroup a good approach for multi-users ?
I will appreciate any feedback given :) Many thanks ! and sorry for my english...