Definition of Database

In Oracle, a database refers to the entire Oracle RDBMS environment and includes these components.

• Oracle database processes and buffers (instance).
• SYSTEM tablespace containing one centralized system catalog.
• Other tablespaces as defined by the DBA (optional).
• Two or more online Redo Logs.
• Archived Redo Logs (optional).
• Miscellaneous other files (control file, Init.ora, and so on).

A Microsoft SQL Server database provides a logical separation of data, applications, and security mechanisms, much like a tablespace. Where Oracle supports multiple tablespaces, SQL Server supports multiple databases. Tablespaces also can be used to support the physical placement of data; SQL Server provides this same functionality with filegroups.

Microsoft SQL Server also installs the following databases by default:

• The model database is a template for all newly created user databases.
• The tempdb database is similar to an Oracle temporary tablespace in that it is used for temporary working storage and sort operations. Unlike the Oracle temporary tablespace, users can create temporary tables that are automatically dropped when the user logs off.
• The msdb database supports the SQL Server Agent and its scheduled jobs, alerts, and replication information.
• The pubs and Northwind databases are provided as sample databases for training.

For more information about the default databases, see SQL Server Books Online.