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Information about Data Model

Database models
Common models
Hierarchical
Network
Relational
Object-relational
Object
Other models
Associative
Concept-oriented
Multi-dimensional
Star schema
XML database


A data model is an abstract model that describes how data is represented and used.

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 modeling.

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 entities or objects modeled by the database.
  • The integrity part: a collection of rules governing the constraints placed on these data structures to ensure structural integrity.
  • The manipulation 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 based on a modified concept of the mathematical relation; the integrity part is expressed in first-order logic and the manipulation part is expressed using the relational algebra, tuple calculus and domain calculus.

Data Model Instance

Data modeling is the process of creating a data model instance by applying a data model theory. This is typically done to solve some business enterprise requirement.

Business requirements are normally captured by a semantic logical data model. This is transformed into a physical data model instance from which is generated a physical database. For more information on the tools and techniques of data modelling, see data modelling.

For example, a data modeler may use a data modeling tool to create an ERD of the Corporate data repository of some business enterprise. This model is transformed into a relational model, which in turn generates a relational database.

External links

  • RFC 3444 - On the Difference between Information Models and Data Models

See also

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

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In a hierarchical data model, data are organized into a tree-like structure. The structure allows repeating information using parent/child relationships: each parent can have many children but each child only has one parent.
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The network model is a database model conceived as a flexible way of representing objects and their relationships. Its original inventor was Charles Bachman, and it was developed into a standard specification published in 1969 by the CODASYL Consortium.
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The relational model for database management is a database model based on predicate logic and set theory. It was first formulated and proposed in 1969 by Edgar Codd with aims that included avoiding, without loss of completeness, the need to write computer programs to
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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.
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'' In an object oriented database, information is represented in the form of objects'' as used in Object-Oriented Programming. When database capabilities are combined with object programming language capabilities, the result is an object database management system (ODBMS).
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The associative model of data is an alternative data model for database systems. Other data models, such as the relational model and the object data model, are record-based. These models involve encompassing attributes about a thing, such as a car, in a record structure.
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The concept-oriented data model is a data model based on lattice theory and ordered sets. Another source of inspiration in creating this model is formal concept analysis (FCA).
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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 give a high degree of
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The star schema (sometimes referenced as star join schema) is the simplest style of data warehouse schema, consisting of a few "fact tables" (possibly only one, justifying the name) referencing any number of "dimension tables".
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XML-enabled. These map all XML to a traditional database (such as a relational database), accepting XML as input and rendering XML as output.
  • Native XML (NXD) The internal model of such databases depends on XML and uses XML documents as the fundamental unit of storage.
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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

    ..... Click the link for more information.
    In computer science, data modeling is the process of creating a data model by applying a data model theory to create a data model instance. A data model theory is a formal data model description. See database model for a list of current data model theories.
    ..... Click the link for more information.
    The relational model for database management is a database model based on predicate logic and set theory. It was first formulated and proposed in 1969 by Edgar Codd with aims that included avoiding, without loss of completeness, the need to write computer programs to
    ..... Click the link for more information.
    relation or relationship is a generalization of 2-place relations, such as the relation of equality, denoted by the sign "=" in a statement like "5 + 7 = 12," or the relation of order,
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    First-order logic (FOL) is a formal deductive system used by mathematicians, philosophers, linguists, and computer scientists. It goes by many names, including: first-order predicate calculus (FOPC), the lower predicate calculus,
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    Relational algebra, an offshoot of first-order logic, is a set of relations closed under operators. Operators operate on one or more relations to yield a relation. Relational algebra is a part of computer science.
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    The tuple 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.
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    In computer science, domain relational calculus (DRC) is a calculus that was introduced by Michel Lacroix and Alain Pirotte as a declarative database query language for the relational data model [1].
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    In computer science, data modeling is the process of creating a data model by applying a data model theory to create a data model instance. A data model theory is a formal data model description. See database model for a list of current data model theories.
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    In computer science, a logical data model also referred to as LDM, is a representation of an organization's data, organized in terms of a particular data management technology.
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    database is a structured collection of records or data that is stored in a computer system so that a computer program or person using a query language can consult it to answer queries. The records retrieved in answer to queries are information that can be used to make decisions.
    ..... Click the link for more information.
    In computer science, data modeling is the process of creating a data model by applying a data model theory to create a data model instance. A data model theory is a formal data model description. See database model for a list of current data model theories.
    ..... Click the link for more information.
    In computer science, data modeling is the process of creating a data model by applying a data model theory to create a data model instance. A data model theory is a formal data model description. See database model for a list of current data model theories.
    ..... Click the link for more information.
    The introduction to this article provides insufficient context for those unfamiliar with the subject matter.
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    A Corporate Data Repository (CDR) is a corporate database or information system used to integrate the information system resources of an organization by sharing a common data model.
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    The relational model for database management is a database model based on predicate logic and set theory. It was first formulated and proposed in 1969 by Edgar Codd with aims that included avoiding, without loss of completeness, the need to write computer programs to
    ..... Click the link for more information.
    A relational database is a database that conforms to the relational model, and refers to a database's data and schema (the database's structure of how that data is arranged).
    ..... Click the link for more information.
    In computer science, data modeling is the process of creating a data model by applying a data model theory to create a data model instance. A data model theory is a formal data model description. See database model for a list of current data model theories.
    ..... Click the link for more information.
    A data dictionary is a set of metadata that contains definitions and representations of data elements. Within the context of a DBMS, a data dictionary is a read-only set of tables and views.
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