These interfaces can account for between 25-70% of the cost of current systems". The result of this is that complex interfaces are required between systems that share data. "Data models for different systems are arbitrarily different.This can lead to replication of data, data structure, and functionality, together with the attendant costs of that duplication in development and maintenance". "Entity types are often not identified, or incorrectly identified.This means that small changes in the way business is conducted lead to large changes in computer systems and interfaces". "Business rules, specific to how things are done in a particular place, are often fixed in the structure of a data model.A major cause is that the quality of the data models implemented in systems and interfaces is poor". They may also constrain the business rather than support it. However, systems and interfaces often cost more than they should, to build, operate, and maintain. If the same data structures are used to store and access data then different applications can share data. According to West and Fowler (1999) "if this is done consistently across systems then compatibility of data can be achieved. The main aim of data models is to support the development of information systems by providing the definition and format of data. They typically do not describe unstructured data, such as word processing documents, email messages, pictures, digital audio, and video. Data models describe the structure, manipulation and integrity aspects of the data stored in data management systems such as relational databases. Managing large quantities of structured and unstructured data is a primary function of information systems.
This article uses the term in both senses. So the "data model" of a banking application may be defined using the entity-relationship "data model". At other times it refers to the set of concepts used in defining such formalizations: for example concepts such as entities, attributes, relations, or tables. Sometimes it refers to an abstract formalization of the objects and relationships found in a particular application domain: for example the customers, products, and orders found in a manufacturing organization. The term data model can refer to two distinct but closely related concepts. For instance, a data model may specify that the data element representing a car be composed of a number of other elements which, in turn, represent the color and size of the car and define its owner. Model that organizes elements of data and how they relate to one another and to real-world entities.Ī data model (or datamodel) is an abstract model that organizes elements of data and standardizes how they relate to one another and to the properties of real-world entities.