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Information about Network Model

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


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. Where the hierarchical model structures data as a tree of records, with each record having one parent record and many children, the network model allows each record to have multiple parent and child records, forming a lattice structure.

The chief argument in favour of the network model, in comparison to the hierarchic model, was that it allowed a more natural modeling of relationships between entities. Although the model was widely implemented and used, it failed to become dominant for two main reasons. Firstly, IBM chose to stick to the hierarchical model with semi-network extensions in their established products such as IMS and DL/I. Secondly, it was eventually displaced by the relational model, which offered a higher-level, more declarative interface. Until the early 1980s the performance benefits of the low-level navigational interfaces offered by hierarchical and network databases were persuasive for many large-scale applications, but as hardware became faster, the extra productivity and flexibility of the relational model replaced the network model in corporate enterprise usage.

History

In 1969, the Conference on Data Systems Languages (CODASYL) established the first specification of the network database model. This was followed by a second publication in 1971, which became the basis for most implementations. Subsequent work continued into the early 1980s, culminating in an ISO specification, but this had little influence on products.

Some Well-known Network Databases

See also

References

External links

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 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.
    Charles W. Bachman
    Born November 11 1924 (1924--) (age 84)
    Manhattan, Kansas
    Nationality American
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    19th century - 20th century - 21st century
    1930s  1940s  1950s  - 1960s -  1970s  1980s  1990s
    1966 1967 1968 - 1969 - 1970 1971 1972

    Also:
    *:1969 (number)
    *:

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    CODASYL (often spelt Codasyl) is an acronym for "Conference on Data Systems Languages". This was an IT industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers.
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    tree is a widely-used data structure that emulates a tree structure with a set of linked nodes.

    Nodes

    A node may contain a value or a condition or represents a separate data structure or a tree of its own.
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    lattice is a partially ordered set (or poset) in which every pair of elements has a unique supremum (the elements' least upper bound; called their join) and an infimum (greatest lower bound; called their meet).
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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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    IBM Information Management System (IMS) is a joint hierarchical database and information management system with extensive transaction processing capability.

    IBM designed IMS with Rockwell and Caterpillar starting in 1966 for the Apollo program.
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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.
    19th century - 20th century - 21st century
    1930s  1940s  1950s  - 1960s -  1970s  1980s  1990s
    1966 1967 1968 - 1969 - 1970 1971 1972

    Also:
    *:1969 (number)
    *:

    ..... Click the link for more information.
    CODASYL (often spelt Codasyl) is an acronym for "Conference on Data Systems Languages". This was an IT industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers.
    ..... Click the link for more information.
    19th century - 20th century - 21st century
    1940s  1950s  1960s  - 1970s -  1980s  1990s  2000s
    1968 1969 1970 - 1971 - 1972 1973 1974

    Year 1971 (MCMLXXI
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    International Organization for Standardization (Organisation internationale de normalisation), widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations.
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    IMAGE is the primary reason that the HP3000 was a success. It is a reliable, simple, fast database for MPE. After about a decade of enhancements it was renamed TurboIMAGE, then TurboIMAGE/XL after the PA-RISC migration.
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    IDMS (Integrated Database Management System) is a (network) CODASYL database management system first developed at B.F. Goodrich and later marketed by Cullinane Database Systems (renamed Cullinet in 1983).
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    CODASYL (often spelt Codasyl) is an acronym for "Conference on Data Systems Languages". This was an IT industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers.
    ..... Click the link for more information.
    Navigational databases incorporate both the network model and hierarchical model of database interfaces and have evolved into Set-oriented systems [1]. Navigational techniques use "pointers" and "paths" to navigate among data records (also known as "nodes").
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    The semantic web is an evolving extension of the World Wide Web in which web content can be expressed not only in natural language, but also in a format that can be read and used by software agents, thus permitting them to find, share and integrate information more easily.
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    The A.M. Turing Award is given annually by the Association for Computing Machinery to a person selected for contributions of a technical nature made to the computing community. The contributions should be of lasting and major technical importance to the computer field.
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    An ISSN, or International Standard Serial Number, is a unique eight-digit number used to identify a print or electronic periodical publication. The ISSN system was adopted as international standard ISO 3297 in 1975. The TC 46/SC 9 is responsible for the standard.
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