Conceptual schema

Conceptual schema

A conceptual schema or conceptual data model is a map of concepts and their relationships. This describes the semantics of an organization and represents a series of assertions about its nature. Specifically, it describes the things of significance to an organization (entity classes), about which it is inclined to collect information, and characteristics of (attributes) and associations between pairs of those things of significance (relationships).

Contents

Overview

Because a conceptual schema represents the semantics of an organization, and not a database design, it may exist on various levels of abstraction. The original ANSI four-schema architecture began with the set of external schemas that each represent one person's view of the world around him or her. These are consolidated into a single conceptual schema that is the superset of all of those external views. A data model can be as concrete as each person's perspective, but this tends to make it inflexible. If that person's world changes, the model must change. Conceptual data models take a more abstract perspective, identifying the fundamental things, of which the things an individual deals with are just examples.

The model does allow for what is called inheritance in object oriented terms. The set of instances of an entity class may be subdivided into entity classes in their own right. Thus, each instance of a sub-type entity class is also an instance of the entity class's super-type. Each instance of the super-type entity class, then is also an instance of one of the sub-type entity classes.

Super-type/sub-type relationships may be exclusive or not. A methodology may require that each instance of a super-type may only be an instance of one sub-type. Similarly, a super-type/sub-type relationship may be exhaustive or not. It is exhaustive if the methodology requires that each instance of a super-type must be an instance of a sub-type.

Example relationships

  • Each PERSON may be the vendor in one or more ORDERS.
  • Each ORDER must be from one and only one PERSON.
  • PERSON is a sub-type of PARTY. (Meaning that every instance of PERSON is also an instance of PARTY.)
  • Each Employee may have the supervisor within Employee.

Data structure diagram

Data Structure Diagram.

A data structure diagram (DSD) is a data model or diagram used to describe conceptual data models by providing graphical notations which document entities and their relationships, and the constraints that binds them.

See also

References

Further reading

  • Perez, Sandra K., & Anthony K. Sarris, eds. (1995) Technical Report for IRDS Conceptual Schema, Part 1: Conceptual Schema for IRDS, Part 2: Modeling Language Analysis, X3/TR-14:1995, American National Standards Institute, New York, NY.

External links


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • conceptual schema — koncepcinis duomenų modelis statusas T sritis dirbtinis intelektas apibrėžtis Taikomosios srities, kurios duomenų bazė kuriama, pagrindinių sąvokų (konceptų) ir jų tarpusavio ryšių visumos atvaizdas – formalus koncepcinio modelio aprašas.… …   Lithuanian dictionary (lietuvių žodynas)

  • conceptual schema — noun A map of concepts, their properties, the relationships between the concepts and the properties of the relationships. Syn: conceptual data model …   Wiktionary

  • Conceptual graph — Conceptual graphs (CGs) are a formalism for knowledge representation. In the first published paper on CGs, John F. Sowa (Sowa 1976) used them to represent the conceptual schemas used in database systems. The first book on CGs (Sowa 1984) applied… …   Wikipedia

  • Conceptual system — A conceptual system is a system that is composed of non physical objects, i.e. ideas or concepts. In this context a system is taken to mean an interrelated, interworking set of objects . Contents 1 Overview 1.1 Examples 2 Related topics …   Wikipedia

  • Conceptual model — For other uses, see Model (disambiguation). In the most general sense, a model is anything used in any way to represent anything else. Some models are physical objects, for instance, a toy model which may be assembled, and may even be made to… …   Wikipedia

  • Conceptual framework — For the concept in aesthetics and art criticism, see The Conceptual Framework. For the concept in computing, see Conceptual schema. For the concept in philosophy, see Paradigm. A conceptual framework is used in research to outline possible… …   Wikipedia

  • conceptual data model — koncepcinis duomenų modelis statusas T sritis dirbtinis intelektas apibrėžtis Taikomosios srities, kurios duomenų bazė kuriama, pagrindinių sąvokų (konceptų) ir jų tarpusavio ryšių visumos atvaizdas – formalus koncepcinio modelio aprašas.… …   Lithuanian dictionary (lietuvių žodynas)

  • Conceptual metaphor — In cognitive linguistics, conceptual metaphor, or cognitive metaphor, refers to the understanding of one idea, or conceptual domain, in terms of another, for example, understanding quantity in terms of directionality (e.g. prices are rising ). A… …   Wikipedia

  • Schema (Kant) — In Kantian philosophy, a schema (plural: schemata ) is the procedural rule by which a category or pure, non empirical concept is associated with a mental image of an object. It is supposedly produced by the imagination through the pure form of… …   Wikipedia

  • schema — /skee meuh/, n., pl. schemata /skee meuh teuh/ or, sometimes, /skee mah teuh, ski /, schemas. 1. a diagram, plan, or scheme. 2. an underlying organizational pattern or structure; conceptual framework. 3. (in Kantian epistemology) a concept,… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”