Adds the specified collection to this context. All contained entities are added to the context as well, if they're not already in the / a context. This will make sure that any entity added to the entity collection will be added to this context as well.

Adds the specified entity to the Context. If the passed in entity is already in a context, the Add is a no-op. Also if the entity isn't new and there is already an entity with the same PK values, the Add is a no-op.