Expansion of RDBMS.  See RelationalDatabase

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A RelationalDataBaseManagementSystem is a software application that allows the maintenance of one or more RelationalDatabase''''''s, and provides lots of additional services such as persistence, transaction management, security, development and administration tools, and the like.  Examples include:

* Informix
* DB2
* OracleDatabase
* MicroSoft SqlServer
* MySql
* PostgreSql
* MicrosoftAccess 
* TdbEngine
* Rel (see RelProject)

In addition, there are numerous NimbleDatabase libraries that can be linked into your application, and some programming languages such as FoxPro provide database functionality as part of the language.