Database Management

A database management system (DBMS) is computer software, which manages databases. The main purpose of each DBMS is to control the organization, storage, management, and retrieval of data in a database. It involves:

• Enabling simple access to data (data is organized in structures)
• Allowing concurrent information access by multiple users (client-server architecture, transactions)
• Manipulating the data found in the database (inserting, deleting, editing)
• Data security (authorization, access control)
• Failure tolerance (archiving, logging)

Each database management system consists of four main components: modeling language, data structure, database query language, and transaction mechanisms.

A data modeling language defines the schema of each database hosted in the database management system, according to the DBMS database model. Relational model, which stores data in tables containing rows and columns, is the most common one. Other common types include the hierarchical model, the network model and the object model. A particular database management system can support either a single or a number of different models.

Data structures (fields, records, files and objects) are optimized to deal with very large amounts of data stored in a permanent data storage device.

A database query language and report writer allows users to interactively interrogate the database, analyze its data and update them according to the users privileges on the data. SQL is the most commonly used query language as it is supported by the majority of existing DBMS’s.

A database transaction mechanism ensures data integrity despite concurrent user accesses (concurrency control), and faults (fault tolerance).

There are variety of DBMSs on the market. The most popular database management systems include:

• Oracle
• Teradata
• IBM DB2
• Microsoft SQL Server
• Firebird
• MySQL
• Sybase