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A database is a collection of data stored together as a unit. Databases are useful for storing data and making it available for retrieval. Within the database, data is organized into different tables. Each table has columns and rows. Indexes on tables provide speedy access to data. Information in the database can be retrieved, modified, or deleted using a query language like SQL.

Some of common database systems are the Oracle database, SQL Server, DB2, Sybase, etc.

Types of Databases[edit]

There are several types of databases available:

  • Flat File Databases
  • Relational Databases
  • Object Oriented Databases
  • Hierarchical Databases

Flat File Databases[edit]

A flat file database is described by a very simple database model where all the information is stored in text files.

Examples of Flat File Databases:

Relational Databases[edit]

Examples of Relational Databases:

For more info, see Relational Database Systems.

Object Oriented Databases[edit]

Examples of Object Oriented Databases:

Hierarchical Databases[edit]

The hierarchical model is considered outdated, has too many limitations, and are not frequently used anymore.

Examples of Hierarchical Databases:

Also see[edit]