Other DBMS systems, such as Object DBMS, offer specific features for more specialized requirements. Most DBMS as of 2009 implement a relational model.
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Almost every database software comes with an Open Database Connectivity (ODBC) driver that allows the database to integrate with other databases. Examples of some commonly used DBMS are MySQL, PostgreSQL, Microsoft Access, SQL Server, FileMaker,Oracle,Sybase, dBASE, Clipper,FoxPro etc. Some DBMS cover more than one entry in these categories, e.g., supporting multiple query languages. Database management systems can be categorized according to the database model that they support, such as relational or XML, the type(s) of computer they support, such as a server cluster or a mobile phone, the query language(s) that access the database, such as SQL or XQuery, performance trade-offs, such as maximum scale or maximum speed or others. It provides a common view of the database that is uncomplicated by details of how the data is stored or managed, and that can unify the various external views into a coherent whole.Ī database management system (DBMS) consists of software that operates databases, providing storage, access, security, backup and other facilities. The conceptual is a level of indirection between internal and external. Internal architecture is concerned with cost, performance, scalability and other operational matters. The internal level defines how the data is physically stored and processed by the computing system.
A single database can have any number of views at the external level. The external level defines how users understand the organization of the data. Clearly separating the three levels was a major feature of the relational database model that dominates 21st century databases. Database architecture consists of three levels, external, conceptual and internal.
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