this wiki
Assessment 
Biopsychology 
Comparative 
Cognitive 
Developmental 
Language 
Individual differences 
Personality 
Philosophy 
Social 
Methods 
Statistics 
Clinical 
Educational 
Industrial 
Professional items 
World psychology 
Statistics: Scientific method · Research methods · Experimental design · Undergraduate statistics courses · Statistical tests · Game theory · Decision theory
Database models 



A data model is an abstract model that describes how data are represented and used.
The term data model has two generally accepted meanings:
 A data model theory i.e. a formal description of how data may be structured and used. See also database model
 A data model instance i.e. applying a data model theory to create a practical data model instance for some particular application. See data modeling.
Contents
[show]Data Model Theory
A data model theory has three main components:
 The structural part: a collection of data structures which are used to create databases representing the entites or objects modelled by the database.
 The integrity part: a collection of rules governing the constraints placed on these data structures to ensure structural integrity.
 The manipulation part: a collection of operators which can be applied to the data structures, to update and query the data contained in the database.
For example, in the relational model, the structural part is based on a modified concept of the mathematical relation; the integrity part is expressed in firstorder logic and the manipulation part is expressed using the relational algebra, tuple calculus and domain calculus.
Data Model Instance
Data modelling is the process creating a data model instance by applying a data model theory. This is typically done to solve some business enterprise requirement.
Business requirements are normally captured by a logical semantic data model. This is transformed into a physical data model instance from which is generated a physical database. For more information on the tools and techniques of data modelling, see data modelling.
For example, a data modeller may use the ERwin data modelling tool to create an ERD of the corporate data model of some business enterprise. This model is transformed into a relational model, which in turn generates a Oracle relational database.
See also
 Data modeling
 Data dictionary
 Diagram
 information system
 database management system
 Information model
 Ontology
 XML schema
References & Bibliography
Key texts
Books
Papers
Additional material
Books
Papers
External links
 RFC 3444  On the Difference between Information Models and Data Models
This page uses Creative Commons Licensed content from Wikipedia (view authors). 