RDBMS

A relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model as introduced by E. F. Codd. Most popular commercial and open source databases currently in use are based on the relational database model.
A short definition of an RDBMS may be a DBMS in which data is stored in the form of tables and the relationship among the data is also stored in the form of tables.

Oracle database

A relational database management system (DBMS) from Oracle, which runs on more than 80 platforms. Introduced in the late 1970s, Oracle was the first database product to run on a variety of platforms from micro to mainframe. The Oracle database is Oracle's flagship product, and version 11g was introduced in 2007.

Oracle 11g features include built-in testing for changes, the capability of viewing tables back in time, superior compression of all types of data and enhanced disaster recovery functions.

The "i" ,"g"and "c" Versions
Starting in 1999 with Version 8i, Oracle added the "i" to the version name to reflect support for the Internet with its built-in Java Virtual Machine (JVM). Oracle 9i added more support for XML in 2001. In 2003, Oracle 10g was introduced with emphasis on the "g" for grid computing, which enables clusters of low-cost, industry standard servers to be treated as a single unit.Further development lead to 11g in 2007 which slowly got developed to 12c.12c features Multi-Tenancy, CDB vs. PDB (CDB is an acronym for “Container Database” and PDB is an acronym for “Pluggable Database”),Split Data Dictionary,Faster Provisioning, Database Administration & Granularity Control Patching & Upgrades are some of its features.

Java Built In
With a JVM (Java interpreter) built into the DBMS, triggers and stored procedures can be written and executed in Java rather than Oracle's PL/SQL programming language. It enables Internet developers to write applications and database procedures in the same language. In addition, the JVM can also execute Enterprise JavaBeans (EJBs), turning the DBMS into an application server.

A database is an organized collection of data. The data is typically organized to model relevant aspects of reality (for example, the availability of rooms in hotels), in a way that supports processes requiring this information (for example, finding a hotel with vacancies).
Wherever there is a system management of the same is required.This requirement gave rise to database management system.
A collection of programs that enables you to store, modify, and extract information from a database. There are many different types of DBMSs, ranging from small systems that run on personal computers to huge systems that run on mainframes. The following are examples of database applications:

computerized library systems

• automated teller machines

flight reservation systems

• computerized parts inventory systems

From a technical standpoint, DBMSs can differ widely. The terms relational, network, flat, and hierarchical all refer to the way a DBMS organizes information internally. The internal organization can affect how quickly and flexibly you can extract information.
Requests for information from a database are made in the form of a query, which is a stylized question. For example, the query
select * from employee where emp_name ='&emp';
 this will return from the employee table the row which has emp_name as the one entered during run time.
The set of rules for constructing queries is known as a query language. Different DBMSs support different query languages, although there is a semi-standardized query language called SQL (structured query language). Sophisticated languages for managing database systems are called fourth-generation languages, or 4GLs for short.
The information from a database can be presented in a variety of formats. Most DBMSs include a report writer program that enables you to output data in the form of a report. Many DBMSs also include a graphics component that enables you to output information in the form of graphs and charts.