Data Model is basically an abstract model that is used in software engineering. It describes the representation and accession of data. Data models are used for defining the data elements and relationship among the data elements for a specific domain.
There are a number of data models that are used to describe how a database is structures and used, these are"
- Flat Model
- Hierarchical Model
- Network Model
- Relational Model
- Object Relational Model
- Star Schema
A model is an abstraction process that hides data storage details while showing details pertinent to the application.
A data model is a mechanism that provide this abstraction for data base application.
A representation of a real world process, device or concept is known as model. For example: An atomic model to show the orbital movement of electrons around the nucleus or nuclear model to show the process of nuclear reactor.A data model (or database model) is a collection of concepts that can be used to describe the structure of a database.
It means that the data types, relationships between data, and constraints that should hold on the data are described. The majority of the data models also contain a set of basic operations for specify retrievals and updates procedures on the database.The purpose of a data model is to represent data and to make the data understandable. By using the data model, you can easily design a database. A data model can be divided into three parts these are:
(I) A structural part, which consists of a set of rules according to which databases can be created.
(ii) A manipulating part, which defines the types of operations that are allowed on the data such as retrieving data from database, updating data, changing the structure of database etc.
(iii) A set of integrity rules, which ensure that the data in database is accurate.
We can define data model as group of concepts used to describe the structure of a database. Here structure of database refers to data types, relationships and constraints that must hold for the data. Some data models also include basic operations for updating and retrieving data. Data model also allow a database designer to specify user defined operations.
These user defined operations are allowed on database objects. For example a user defined operation could be compute salary which can be applied to a clerk object. Options like insert, delete, and update are also included in basic data model operations. A data model not only contains the basic operations but it also contains some concepts to specify the dynamic behavior of a database application. Many data models have been proposed, which we can categorized according to the types of concepts they used to describe the database structure.
Three types of data models are used including, high level or conceptual data model, lower or physical data model and representational or implementation data model. Each data model has some specific operations used for different purposes. In any data model, it is important to distinguish between the description of the database and database itself. Description of database is called database schema.
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