I am developing an application which allows 'users' to create 'lists'. I have a many-to-many relationship between 'users' and 'lists' (this might not be right). Additionally 'Lists' have many 'Tasks'.
What I would like to do is extend this model to include the idea of 'invitations'. I would like users to be able to invite one another to other lists. A user can create many invitations. A user can create an 'invitation' and the invitation would have one or many 'invitees' which, in turn, would be 'Users'. So am confused about how this should be organized in a relational db.
I think the core problem is: users 'own' invitations but also can be the recipient of an invitation. Clear as mud? :)
I was hoping someone could offer some advice on how this might be accomplished. Any example ERDs would be useful. If my question requires further clarification I can provide it.