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Database



A Database is a collection of information stored in a way that makes it easy to retrieve, modify and search. A database can be stored in a single file with all the information stored together in a single table which is called a flat database or stored in multiple tables with some common access information referred to as a relational database.

The term database is correctly applied to the data and their supporting data structures, and not to the database management system (referred to by the acronym DBMS). The database data collection with DBMS is called a database system.

Well known DBMSs include Oracle, IBM DB2, Microsoft SQL Server, PostgreSQL, MySQL and SQLite. A database is not generally portable across different DBMS, but different DBMSs can inter-operate to some degree by using standards like SQL and ODBC to support together a single application.

The design, construction, and maintenance of a complex database requires specialist skills: the staff performing these functions are referred to as database application programmers and database administrators. Their tasks are supported by tools provided either as part of the DBMS or as stand-alone software products.

These tools include specialized database languages including :
  • Data definition languages (DDL),
  • Data manipulation languages (DML),
  • query languages.

Three types of people are involved with a general-purpose DBMS :
  • DBMS developers - These are the people that design and build the DBMS product, and the only ones who touch its code. They are typically the employees of a DBMS vendor (e.g., Oracle, IBM, Microsoft, Sybase), or, in the case of Open source DBMSs (e.g., MySQL), volunteers or people supported by interested companies and organizations. They are typically skilled systems programmers.

  • Application developers and Database administrators - These are the people that design and build a database-based application that uses the DBMS. The latter group members design the needed database and maintain it. The first group members write the needed application programs which the application comprises. Both are well familiar with the DBMS product and use its user interfaces (as well as usually other tools) for their work.

  • Application's end-users (e.g., accountants, insurance people, medical doctors, etc.) - These people know the application and its end-user interfaces, but need not know nor understand the underlying DBMS. Thus, though they are the intended and main beneficiaries of a DBMS, they are only indirectly involved with it.

Types  of  Database

Data warehouses archive data from operational databases and often from external sources such as market research firms. Often operational data undergoes transformation on its way into the warehouse, getting summarized, anonymized, reclassified, etc. The warehouse becomes the central source of data for use by managers and other end-users who may not have access to operational data.

A distributed database is broad, and may be utilized in different meanings. In general it typically refers to a modular DBMS architecture that allows distinct DBMS instances to cooperate as a single DBMS over processes, computers, and sites, while managing a single database distributed itself over multiple computers, and different sites.

Examples are databases of local work-groups and departments at regional offices, branch offices, manufacturing plants and other work sites. These databases can include both segments shared by multiple sites, and segments specific to one site and used only locally in that site.

An embedded database system is a DBMS which is tightly integrated with an application software that requires access to stored data in a way that the DBMS is “hidden” from the application’s end-user and requires little or no ongoing maintenance. It is actually a broad technology category that includes DBMSs with differing properties and target markets. 

The term "embedded database" can be confusing because only a small subset of embedded database products is used in real-time embedded systems such as telecommunications switches and consumer electronics devices.

Operational database store detailed data about the operations of an organization. They are typically organized by subject matter, process relatively high volumes of updates using transactions. Essentially every major organization on earth uses such databases.

Examples include customer databases that record contact, credit, and demographic information about a business' customers, personnel databases that hold information such as salary, benefits, skills data about employees, Enterprise resource planning that record details about product components, parts inventory, and financial databases that keep track of the organization's money, accounting and financial dealings.



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