Differences between Object Views and Object Tables:

Additionally to the obvious difference among a view and a table, more subtle differences exist among an object view and an object table. An area of difference involves:

• Uniqueness of object identifiers. While object tables always have unique OIDs that are possible to create object views that contain duplicate virtual OIDs. The Object views might also duplicate the OIDs of other object views or object tables.
• Use of REFs. As with an object table, that is possible to use a REF to point to an example of an object view. Therefore, these REFs must be constructed from foreign keys with the special built-in MAKE_REF, that turns out to be a rather finicky function. In particular, if you're foreign key value is null and MAKE_REF returns an error!
• The Storage of REFs. Object tables can store REF values persistently but REFs to virtual objects in an object view must be constructed dynamically (with MAKE_REF).
• REFs to Non-Unique OIDs. It is not possible in an object table to have a REF to a non- unique OID; but an object view that has such a REF may have this problem. You have to think it and deal with it if necessary.