Principal of view equality?

I was just looking at Codd's RM 2 book again (the rather short chapter on views from acm.org) and it seemed to me that what he wrote took it as essential that a view must always equal the expression that defines the view. If so, does this in effect constitute a kind of indirect constraint on any base relations involved?

(Assuming that all relations a dbms stores are to be considered 'true') Received on Tue Jun 03 2008 - 21:53:39 CDT