Encyclopedia > Data model

  Article Content

Data model

A data model is a model that describes in an abstract way how data is represented in an information system or a database. In general it describes the following aspects:
  1. Structure: defines what the structure of the representation is. This should not only specify how data is represented but also how a schema can be specified that defines the structure of the data in a specific user domain.
  2. Integrity: provides a language for the definition of rules that restrict which instances of the defined structure are allowed.
  3. Manipulation: provides a language in which updates of the data can be expressed.
  4. Querying: provides a language in which the data can be queried.

An example is the relational model in which all data is represented by mathematical relations (or, to be precise, a slightly generalized version thereof). It furthermore defines a set of specific constraints (candidate keys[?], foreign keys) and a general language for specifying constraints (first-order logic), and for manipulations and querying the data the relational algebra, tuple calculus and domain calculus are introduced.

Other examples are the Functional Data Model[?], the Entity-Relationship Model[?] and the Object Role Model[?] although these usually only describe a small subset of the aspects described above.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
1904

... cylinder. March 4 - Russo-Japanese War: Russian troops in Korea retreat toward Manchuria followed by 100,000 Japanese troops. April 30 - Louisiana Purchase ...

 
 
 
This page was created in 39.1 ms