Data model: Difference between revisions

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Latest revision as of 11:53, 21 August 2025

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Bill Kent, in his 1978 book ''Data and Reality,''<ref>{{citation|title=Data and Reality |url=http://www.bkent.net/Doc/darxrp.htm}}</ref> compared a data model to a map of a territory, emphasizing that in the real world, "highways are not painted red, rivers don't have county lines running down the middle, and you can't see contour lines on a mountain". In contrast to other researchers who tried to create models that were mathematically clean and elegant, Kent emphasized the essential messiness of the real world, and the task of the data modeler to create order out of chaos without excessively distorting the truth.

In the 1980s, according to Jan L. Harrington (2000), "the development of the [[Object-oriented programming|object-oriented]] paradigm brought about a fundamental change in the way we look at data and the procedures that operate on data. Traditionally, data and procedures have been stored separately: the data and their relationship in a database, the procedures in an application program. Object orientation, however, combined an entity's procedure with its data."<ref name="JLH00">Jan L. Harrington (2000). ''Object-oriented Database Design Clearly Explained''. p.4</ref>

During the early 1990s, three Dutch mathematicians Guido Bakema, Harm van der Lek, and JanPieter Zwart, continued the development on the work of [[G.M. Nijssen]]. They focused more on the communication part of the semantics. In 1997 they formalized the method Fully Communication Oriented Information Modeling [[FCO-IM]].

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: The hierarchical model is similar to the network model except that links in the hierarchical model form a tree structure, while the network model allows arbitrary graph.

; [[Network model]]

: ThisThe [[network model]], also [[graph model]], organizes data using two fundamental constructs, called records and sets. Records (or nodes) contain fields (i.e. attributes), and sets (or edges) define one-to-many, many-to-many and many-to-one relationships between records: one owner, many members. The network data model is an abstraction of the design concept used in the implementation of databases. Network models emphasise interconnectedness, making them ideal for applications where relationships are crucial, like social networks or recommendation systems. This structure allows for efficient querying of relationships without expensive joins.

; [[Relational model]]

: is a database model based on first-order predicate logic. Its core idea is to describe a database as a collection of predicates over a finite set of predicate variables, describing constraints on the possible values and combinations of values. The power of the relational data model lies in its mathematical foundations and a simple user-level paradigm.