I really haven't specified whether all names are visible at any time. By using the Source_From and View_From it isn't necessary to have the set of names be disjoint. How do we define the source and the view? I propose that we adopt the following. When specifying a view a user must indicate that they are building a view by some Start View command. This command will also indicate the source database and the name of the view. If the view already exists then we will consider this command to be the start of some append session - appending to what already lives in the view. Once this is done then names from both the source and the view are visible, but only within their respective scoping.
I have definitely glossed over the issue of grouping. In the query execution engine: select p2, p2.address will behave differently then the Import version. In particular the query engine imposes a grouping while in the import we will lose this grouping. Perhaps there is some case when we don't want to lose the grouping.