ForeignKeyDeclaration are to be manipulated only during the Schema definition (this is why all public methods have the implicit arg (implicit ev: Schema))
For use with View[A] or Table[A], when A extends KeyedEntity[K], lookup and delete by key become implicitly available Example :
This class can be used for read only tables or (database) views for an updatable view, or table use Table[T]
This factory is meant to use POSOs (Plain old Scala Objects), i.