Database Models
Database model provides the necessary means to active data abstraction. There different database models:
- Hierarchical Database model
- Network model
- Relational Database Model
- Object oriented database model
- Object relational database model
- E-R Model
- Hierarchical Database model: Data are arrange in tree like structure which is also called Top Down approach or parent child structure. The entire old models are hierarchical model. The root node may have any number of dependents. In a hierarchical database model the relationship between parents. A parent can have several number of child and child have one parent which establish one to many relationship, and may to many relationship is not in hierarchical model. It is a first generation database model.
- Network Database Model: A data model is an extension or hierarchical database structure. The network model stores a record with link to other record. There exist many to many relationships. It is also first generation database model.
Fig: Network Database Model
- Relational Database Model: The collection of row and column is called table and the table is also called relation. Each row /tuple/record represents an entity and each column or field represents an attributes and entity. Data are organized in different many tables and related to one another. It is a second generation models.
Fig: Relational Database Model
- Object oriented Database model: database that stores data as an object. Uses a object oriented database programming (OOP) concept. It is a third generation database model.
- Object Relational database model: A database that is depending upon a relational database model. It is also Third generation database model.
Fig: object Relational Database model
- E-R Model: it is based on perception of real word that consists of collection of basic object called entity. It is a database modeling technique that is graphically representation of entities and create relationship between these entities. It is a conceptual database model. The basic component of a E-R diagram are:
Example: Teacher and Department
