Oracle 10g makes the transition easier with
object views. Object views allow the object-oriented applications to see the data as a collection
of objects that have attributes and methods, while the legacy systems can still run batch jobs
against the INVENTORY table. Object views can simulate abstract datatypes, object identifiers
(OIDs), and references that a purely OO database environment would provide.
As with regular views, you can use instead of triggers in the view definition to allow DML
against the view by running a block of PL/SQL code instead of the actual DML statement supplied
by the user or application.
Users and Schemas
Access to the database is granted to a database account known as a user. A user may exist in the
database without owning any objects. However, if the user creates and owns objects in the database,
those objects are part of a schema that has the same name as the database user. A schema can own
any type of object in the database: tables, indexes, sequences, views, and so forth. The schema
owner or DBA can grant access to these objects to other database users. The user always has full
privileges and control over the objects in the user??™s schema.
When a user is created by the DBA (or by any other user with the create user system privilege),
a number of other characteristics can be assigned to the user, such as which tablespaces are
available to the user for creating objects, and whether the password is pre-expired.
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