Conceptual schema
Encyclopedia
A conceptual schema or conceptual data model
is a map of concept
s and their relationship
s. This describes the semantics
of an organization and represents a series of assertion
s 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).
, 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.
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.
Data model
A data model in software engineering is an abstract model, that documents and organizes the business data for communication between team members and is used as a plan for developing applications, specifically how data is stored and accessed....
is a map of concept
Concept
The word concept is used in ordinary language as well as in almost all academic disciplines. Particularly in philosophy, psychology and cognitive sciences the term is much used and much discussed. WordNet defines concept: "conception, construct ". However, the meaning of the term concept is much...
s and their relationship
Relational model
The relational model for database management is a database model based on first-order predicate logic, first formulated and proposed in 1969 by Edgar F...
s. This describes the semantics
Semantics
Semantics is the study of meaning. It focuses on the relation between signifiers, such as words, phrases, signs and symbols, and what they stand for, their denotata....
of an organization and represents a series of assertion
Logical assertion
A logical assertion is a statement that asserts that a certain premise is true, and is useful for statements in proof. It is equivalent to a sequent with an empty antecedent....
s about its nature. Specifically, it describes the things of significance to an organization
Organization
An organization is a social group which distributes tasks for a collective goal. The word itself is derived from the Greek word organon, itself derived from the better-known word ergon - as we know `organ` - and it means a compartment for a particular job.There are a variety of legal types of...
(entity classes), about which it is inclined to collect information, and characteristics of (attributes) and associations between pairs of those things of significance (relationships).
Overview
Because a conceptual schema represents the semantics of an organization, and not a database designDatabase design
Database design is the process of producing a detailed data model of a database. This logical data model contains all the needed logical and physical design choices and physical storage parameters needed to generate a design in a Data Definition Language, which can then be used to create a database...
, it may exist on various levels of abstraction. The original ANSI
Ansi
Ansi is a village in Kaarma Parish, Saare County, on the island of Saaremaa, Estonia....
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
Inheritance (computer science)
In object-oriented programming , inheritance is a way to reuse code of existing objects, establish a subtype from an existing object, or both, depending upon programming language support...
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
Subtype
In programming language theory, subtyping or subtype polymorphism is a form of type polymorphism in which a subtype is a datatype that is related to another datatype by some notion of substitutability, meaning that program constructs, typically subroutines or functions, written to operate on...
relationships may be exclusive
Exclusive relationship
In computing, an exclusive relationship is a type of Relationship in computer data base design.In Relational Database Design, in some cases the existence of one kind of relationship type precludes the existence of another. Entities within an entity type A may be related by a relationship type R to...
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 is a data model used to describe conceptual data models by providing graphical notations which document entities and their relationships, and the constraints that binds them....
(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
- Concept mapping
- Conceptual frameworkConceptual frameworkA conceptual framework is used in research to outline possible courses of action or to present a preferred approach to an idea or thought. For example, the philosopher Isaiah Berlin used the "hedgehogs" versus "foxes" approach; a "hedgehog" might approach the world in terms of a single organizing...
- Conceptual graphs
- Data modelingData modelingData modeling in software engineering is the process of creating a data model for an information system by applying formal data modeling techniques.- Overview :...
- Entity-relationship modelEntity-relationship modelIn software engineering, an entity-relationship model is an abstract and conceptual representation of data. Entity-relationship modeling is a database modeling method, used to produce a type of conceptual schema or semantic data model of a system, often a relational database, and its requirements...
- Object-relationship modelling
- Object role modelingObject role modelingObject Role Modeling is a method for conceptual modeling, and can be used as a tool for information and rules analysis, ontological analysis, and data modeling in the field of software engineering.- Overview :...
- Knowledge representationKnowledge representationKnowledge representation is an area of artificial intelligence research aimed at representing knowledge in symbols to facilitate inferencing from those knowledge elements, creating new elements of knowledge...
- Logical data modelLogical data modelA logical data model in systems engineering is a representation of an organization's data, organized in terms of entities and relationships and is independent of any particular data management technology.- Overview :...
- Mindmap
- OntologyOntology (computer science)In computer science and information science, an ontology formally represents knowledge as a set of concepts within a domain, and the relationships between those concepts. It can be used to reason about the entities within that domain and may be used to describe the domain.In theory, an ontology is...
- Physical data modelPhysical data modelA physical data model is a representation of a data design which takes into account the facilities and constraints of a given database management system. In the lifecycle of a project it is typically derived from a logical data model, though it may be reverse-engineered from a given database...
- Semantic WebSemantic WebThe Semantic Web is a collaborative movement led by the World Wide Web Consortium that promotes common formats for data on the World Wide Web. By encouraging the inclusion of semantic content in web pages, the Semantic Web aims at converting the current web of unstructured documents into a "web of...
- Three schema approachThree schema approachThe three-schema approach, or the Three Schema Concept, in software engineering is an approach to building information systems and systems information management from the 1970s...
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
- A different point of view, as described by the "agileAgile software developmentAgile software development is a group of software development methodologies based on iterative and incremental development, where requirements and solutions evolve through collaboration between self-organizing, cross-functional teams...
" community