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A database model is a theory or specification describing how a database is structured and used.
Several such models have been suggested.
Common models include:
- Hierarchical model
- Network model
- Relational model
- Entity-relationship
- Object-Relational model
- Object model
Other models include:
- Associative
- Concept-oriented
- Entity-Attribute-Value
- Multi-dimensional model
- Semantic data model
- Semi-structured
- Star schema
- XML database
Hierarchical Model:
The hierarchical data model organizes data in a tree structure. There is a hierarchy of parent and child data segments. This structure implies that a record can have repeating information, generally in the child data segments. It collects all the instances of a specific record together as a record type.
Network Model:
The popularity of the network data model coincided with the popularity of the hierarchical data model. Some data were more naturally modelled with more than one parent per child. So, the network model permitted the modelling of many-to-many relationships in data. In 1971, the Conference on Data Systems Languages (CODASYL) formally defined the network model.
Relational Model:
RDBMS (relational database management system) is a database based on the relational model developed by E.F. Codd. A relational database allows the definition of data structures, storage and retrieval operations and integrity constraints. In such a database the data and relations between them are organised in tables. A table is a collection of records and each record in a table contains the same fields.
Object/Relational Model:
Object/relational database management systems (ORDBMSs) add new object storage capabilities to the relational systems at the core of modern information systems. These new facilities integrate management of traditional fielded data, complex objects such as time-series and geospatial data and diverse binary media such as audio, video, images, and applets. By encapsulating methods with data structures, an ORDBMS server can execute complex analytical and data manipulation operations to search and transform multimedia and other complex objects.
Object-Oriented Model:
Object DBMSs add database functionality to object programming languages. They bring much more than persistent storage of programming language objects. Object DBMSs extend the semantics of the C++, Smalltalk and Java object programming languages to provide full-featured database programming capability, while retaining native language compatibility.
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