Unlike SQL Server, Oracle does not have the concept of Identity columns. Instead Oracle has concept of sequences. While working with current Oracle Provider for Entity Frameworks, there is no support for specifying these sequences declaratively in the designer. You will definitely have need for inserts in your application.
While performing inserts using EF, we used Oracle Client Library and we wrote functions like
We thought about changing the structure, i.e adding a TRIGGER for inserts and then use the EF designer to specify the id generation declaratively. Finally decided against it (for obvious design reasons).
SQL SERVER 2012 AND SEQUENCE
SQL Server 2012 introduce the concept of the SEQUENCE. If you want to write your ORM layer which supports two (Oracle and SQL Server) of the major RDBMS vendors, you should consider using this feature.