Editing Database (section)

==Database management system==

Connolly and Begg define database management system (DBMS) as a "software system that enables users to define, create, maintain and control access to the database."{{sfn|Connolly|Begg|2014|p=64}} Examples of DBMS's include [[MySQL]], [[MariaDB]], [[PostgreSQL]], [[Microsoft SQL Server]], [[Oracle Database]], and [[Microsoft Access]].

The DBMS acronym is sometimes extended to indicate the underlying [[database model]], with RDBMS for the [[Relational model|relational]], OODBMS for the [[Object model|object (oriented)]] and ORDBMS for the [[object–relational database|object–relational model]]. Other extensions can indicate some other characteristics, such as DDBMS for a distributed database management systems.

The functionality provided by a DBMS can vary enormously. The core functionality is the storage, retrieval and update of data. [[Edgar F. Codd|Codd]] proposed the following functions and services a fully-fledged general purpose DBMS should provide:{{sfn|Connolly|Begg|2014|pp=97–102}}

* Data storage, retrieval and update
* User accessible catalog or [[data dictionary]] describing the metadata
* Support for transactions and concurrency
* Facilities for recovering the database should it become damaged
* Support for authorization of access and update of data
* Access support from remote locations
* Enforcing constraints to ensure data in the database abides by certain rules

It is also generally to be expected the DBMS will provide a set of utilities for such purposes as may be necessary to administer the database effectively, including import, export, monitoring, defragmentation and analysis utilities.{{sfn|Connolly|Begg|2014|p=102}} The core part of the DBMS interacting between the database and the application interface sometimes referred to as the [[database engine]].

Often DBMSs will have configuration parameters that can be statically and dynamically tuned, for example the maximum amount of main memory on a server the database can use. The trend is to minimize the amount of manual configuration, and for cases such as [[embedded database]]s the need to target zero-administration is paramount.

The large major enterprise DBMSs have tended to increase in size and functionality and have involved up to thousands of human years of development effort throughout their lifetime.{{efn|This article quotes a development time of five years involving 750 people for DB2 release 9 alone.{{sfn|Chong|Wang|Dang|Snow|2007}}}}

Early multi-user DBMS typically only allowed for the application to reside on the same computer with access via [[Computer terminal|terminals]] or terminal emulation software. The [[client–server architecture]] was a development where the application resided on a client desktop and the database on a server allowing the processing to be distributed. This evolved into a [[multitier architecture]] incorporating [[application server]]s and [[web server]]s with the end user interface via a [[web browser]] with the database only directly connected to the adjacent tier.{{sfn|Connolly|Begg|2014|pp=106–113}}

A general-purpose DBMS will provide public [[application programming interface]]s (API) and optionally a processor for [[database language]]s such as [[SQL]] to allow applications to be written to interact with and manipulate the database. A special purpose DBMS may use a private API and be specifically customized and linked to a single application. For example, an [[email]] system performs many of the functions of a general-purpose DBMS such as message insertion, message deletion, attachment handling, blocklist lookup, associating messages an email address and so forth however these functions are limited to what is required to handle email.