Oracle developed by Oracle Corporation is the most popular relational database system (RDBMS). Not only Oracle is a RDBMS, but also provides functionality for Cloud, Document Store, Graph DBMS, Key-value storage, BLOG, and PDF Storages. Recently. Oracle just announced an autonomous feature that allows databases to be intelligent and self-managed. Oracle database is a relational database (RDBMS). Relational databases store data in a tabular form of rows and columns. Column of a database table represents the attributes of an entity and rows of a table store records. An RDBMS that implements object-oriented features such as user-defined types, inheritance, and polymorphism is called an object-relational database management system (ORDBMS). Oracle Database has extended the relational model to an object-relational model, making it possible to store complex business models in a relational database. One characteristic of an RDBMS is the independence of physical data storage from logical data structures. In Oracle Database, a database schema is a collection of logical data structures or schema objects. A database user owns a database schema, which has the same name as the user name. Schema objects are user-created structures that directly refer to the data in the database. The database supports many types of schema objects, the most important of which are tables and indexes. A schema object is one type of database object. Some database objects, such as profiles and roles, do not reside in schemas. Database Rank 1 Oracle 1268.84 2 MySQL 1154.27 3 Microsoft SQL Server 1040.26 4 PostgreSQL 466.11 5 MongoDB 387.18 6 IBM Db2 179.85 7 Redis 149.01 8 Elasticsearch 143.44 9 Microsoft Access 141.62 10 SQLite 126.8 ...