This is a simple question yet I was unable to find any information at all about this.
Is it possible to have sub-schemas in SQL Server 2005/2008?
Example:
Having a HR (Human Resources) schema with a sub-schema called Training (with tables related to this). It would end up like HR.Training.* where * would be the tables.
No. You could fake this with roles by putting different users into different roles and allowing those roles to use objects.