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Encyclopedia > Data model
Database models
Common models
Other models

A data model is a model that describes how data are represented and used in an abstract way. A database model is a theory or specification describing how a database is structured and used. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The network model is a database model conceived as a flexible way of representing objects and their relationships. ... The relational model for database management is a database model based on predicate logic and set theory. ... An object-relational database (ORD) or object-relational database management system (ORDBMS) is a relational database management system that allows developers to integrate the database with their own custom data types and methods. ... In an object oriented database, information is represented in the form of objects like in object oriented programming. ... The Associative Model of Data is a data model which, it is claimed, offers numerous advantages over the current industry-leading relational database technology used in the largest percentage of modern database systems. ... The concept-oriented data model is a data model based on lattice theory and ordered sets. ... Multidimensional databases are variously (depending on the context) data aggregators which combine data from a multitude of data sources; databases which offer networks, hierarchies, arrays and other data formats difficult to model in SQL; or databases which offer a high degree of flexibility in the definition of dimensions, units, and... The star schema (sometimes referenced as star join schema) is the simplest data warehouse schema, consisting of a single fact table with a compound primary key, with one segment for each dimension and with additional columns of additive, numeric facts. ... In general, data consist of propositions that reflect reality. ...


The term data model has two generally accepted meanings:

  1. A data model theory i.e. a formal description of how data may be structured and used. See also database model
  2. A data model instance i.e. applying a data model theory to create a practical data model instance for some particular application. See data modelling.

Contents

A database model is a theory or specification describing how a database is structured and used. ... In information system design, data modeling is the analysis and design of the information in the system, concentrating on the logical entities and the logical dependencies between these entities. ...

Data Model Theory

A data model theory has three main components:

  • The structural part: a collection of data structures which are used to create databases representing the entites or objects modelled by the database.
  • The integrity part: a collection of rules governing the constraints placed on these data structures to ensure structural integrity.
  • The manipulative part: a collection of operators which can be applied to the data structures, to update and query the data contained in the database.

For example, in the relational model, the structural part is represented by mathematical relations (or, to be precise, a slightly generalized version thereof); the integrity part is expressed in (first-order logic) and the manipulative part is expressed using the relational algebra, tuple calculus and domain calculus. The relational model for database management is a database model based on predicate logic and set theory. ... In mathematics, a finitary relation is defined by one of the formal definitions given below. ... It has been suggested that Predicate calculus be merged into this article or section. ... Relational algebra, an offshoot of first-order logic, is a set of relations closed under operators. ... This article may be too technical for most readers to understand. ... In computer science, domain relational calculus is a calculus that was introduced by Edgar F. Codd as part of the relational model in order to give a declarative database query language for this data model. ...


Data Model Instance

Data modelling is the process of applying a data model theory to create a data model instance for some practical purpose. For more information on the tools and techniques, see data modelling. In computer science, data modeling is the process of applying a data model theory to create a data model instance. ... In computer science, data modeling is the process of applying a data model theory to create a data model instance. ...


For example, a data modeller may create a Corporate data model (data model instance) for the Corporate data repository of a business. In computer science, data modeling is the process of applying a data model theory to create a data model instance. ... A Corporate Data Repository (CDR) is a corporate database or information system used to integrate the information system resouces of an organisation by sharing a common data model. ...


External links

  • RFC 3198 - Terminology for Policy-Based Management
  • RFC 3444 - On the Difference between Information Models and Data Models

See also


  Results from FactBites:
 
Introduction to Physical Data Model (PDM)s (1773 words)
Data modeling is the act of exploring data-oriented structures.
Physical data modeling is conceptually similar to design class modeling, the goal being to design the internal schema of a database, depicting the data tables, the data columns of those tables, and the relationships between the tables.
Data normalization is a process in which data attributes within a data model are organized to increase the cohesion of tables and to reduce the coupling between tables.
A UML Profile for Data Modeling (3728 words)
Data attributes on conceptual and logical data models, as well as columns on physical data models, are modeled using the standard attribute notation.
Traditional data models typically don’t have a good way of distinguishing which key an attribute or column is a part of, this information is often left for supporting documentation.
It may be a copy of data from another source, a copy that may or may not be automatically replicated, or it may be deprecated and therefore it is suggested that the database element is not accessed at all.
  More results at FactBites »


 

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