Database Types: Hierarchical, Relational, and Network Database (Especially for GATE-Geospatial 2022)

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A database is a collection of non-redundant data which can be shared by different application systems. A collection of multiple files is called database. There are three basic types.

  • Hierarchical Database
  • Relational Database
  • Network Database
This Image Shows Three Types of Database

1. Hierarchical Database

There is a relationship among data called one-to-many or parent-child relationship. A hierarchical database model is a data model in which the data is organized into a tree-like structure. This model is recognized as the first database model created by IBM in the 1960s.

The structure allows representing information using parent/child relationships: each parent can have many children, but each child has only one parent. All attributes of a specific record are listed under an entity type. Each individual record is represented as a row, and each attribute as a column. Entity types are related to each other using 1: N mappings.

Types of Electronics

Example

An organization could store employee information in a table that contains columns such as employee number, first name, last name, and department number. The organization provides each employee with computer hardware as needed, but computer equipment may only be used by the employee to which it is assigned. The organization could store the computer hardware information in a separate table that includes each part՚s serial number, type, and the employee that uses it.

Table Shows Example of Hierarchical Data

In this model, the employee data table represents the “parent” part of the hierarchy, while the computer table represents the “child” part of the hierarchy. As shown, each employee may process several piece of computer equipment, but each individual piece of computer equipment may have only one employee owner.

2. Network Database

The network database model was invented by Charles Bachman in 1969 to enhance the existing hierarchical database model. The network model is a database model conceived as a flexible way of representing objects and their relationships. Its distinguishing feature is that the scheme, viewed as a graph in which object types are nodes and relationship types are arcs, is not restricted to being a hierarchy.

The network model organizes data using two fundamental constructs, called records and sets.

  • Records contain fields.
  • Sets define one-to-many relationships between records
  • One owner, many members: A record may be an owner in any number sets, and a member in any number of sets.

Many GIS databases have many-to-many relationships in which a single entity may have many attributes, and each attribute is linked to many entities. To accommodate these relationships, each individual piece of data can be linked directly anywhere in database, without the existence of a parent child relationship.

Example

Network systems are less rigid and can handle many-to-many relationships. Unlike the hierarchy structure, they reduce redundancy of data.

This Diagram Shows Network Data

3. Relational Database

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. Codd. The purpose of the relational model is to provide a declarative method for specifying data and queries: users directly state what information the database contains and what information they want from it, and let the database management system software take care of describing data structures for storing the data and retrieval procedures for answering queries.

Example

This Diagram Shows Relation Data

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