Database Model and It's type advantage and disadvantage

Database Model

There are different forms of Database Management system. Each characterized by the way where data are defined and structured. This arrangement of data in several structure are known as data base model. Different types of database model.

1.Hierarchical database model

It is one of the oldest type of database model. In this model data are represented in the forms of record, each record has multiple field or attributes. All records are arranged in database as tree like structure.

The relationship between the records is called parent child relationship in which one child record relates to only a single parent i.e child posses property only property of a single parent. Here child are restricted to use the property of a parent to whom it doesn't belong.

Important Point to remember

• A hierarchical database model is a data model in which the data are organized into a tree-like structure
• Data are stored as records which are connected to one another through links.
• Each node is related to others in parent-child relationship.
• conventional database model.

Advantages

• Easiest model of database
• Secure because nobody can modify a child without accessing its parent
• Searching is fast and easy if parent is known
• Efficient on one-to-many relationship
• It supports one to one or one to many relationships.

Disadvantages

• It is an old fashion and outdated database model.
• It doesn’t support many to one relationship.
• It doesn’t reduce data redundancy because some data are written over different places.
• non-flexible
• Cannot handle many to many relationship
• If parent is deleted, all the child nodes will be deleted.
• Increases data redundancy. 

2.Network database model

This network model replace hierarchical model due to some limitation on the model. Suppose an employee relates to two different department then hierarchical model cannot be able to arrange record in proper place. So, network database model was emerged to arrange non-hierarchical database. The structure of database is more like graph rather than tree structure. A network model consists of collection of record which are interrelated to each other with the help of relationship. Each records have multiple fields and each field has only one data value. In this type of model a parent may have multiple child, as well as child can have multiple parent.

Important Point to remember

• Modified model of hierarchical model
• Each node may have several parents
• Higher level of flexibility than hierarchical
• Easier to restructure
• Becomes complicated according to the increment in network
• Less user friendly than hierarchical

Advantages

• More flexible than hierarchical because of many to many relationships.
• It reduces data redundancy.
• This network mode is simple and easy to design.
• Searching is faster due to use of multi-directional pointer.
• Reduces redundancy

Disadvantages

• Lack of structural independence.
• Complex database model
• Needs larger program to handle relationship
• Less secure than hierarchical

3.Relational database model

In relational database model, the data are organized into tables which contains multiple row and columns. These tables are called relations. A row in a table represents a relationship among a set of values. Since, a table is collection of such relationship. It is generally referred to the mathematical term relations from which the relational database model derives its name. It is also known as RDBMS. Data are arranged in two-dimensional table which are easy for user to develop and understand.

The basic data structure of relational data base is the table. Data is presented as relationship or table of two dimension formed by rows and columns rows are also called records or tuples. The relationship identifies a set of entities(tuples) of the same type.

Note: The database system which stores and display data in tabular format of rows and column like spreadsheet is known as RDBMS. It is the most practical DBMS those days. For example, MS-Access, MY SQL, Oracle etc.

Important point to remember

• Relational Model (RM) represents the database as a collection of relations.
• A relation is nothing but a table of values.
• Every row in the table represents a collection of related data values.
• These rows in the table denote a real-world entity or relationship.

Advantages

• There is less data redundancy.
• Breaking of complex database into simple is very much easier.
• Database processing is faster than other model.
• easy to use
• Flexible
• Data independence is achieved more easily.
• security control and authorization can also be implemented

Disadvantage

• Establishing more relationships complex.
• It requires powerful computer and data storage device.
• Expensive to setup
• It is very difficult to scale as much as a database grows larger.
• Difficult to connect the multiple databases

4.Object oriented database model

An object-oriented database is a database that subscribes to a model with information represented by objects. Object is any real things that are available in the world which has own data and method so, is independent.

Therefore, objects contain both executable code and data. There are other characteristics of objects such as whether methods or data can be accessed from outside the object.

Advantage of OOM

• Have reusability features
• More flexible in case of any change
• Code is reused because of inheritance
• Since each class binds its attribute and function so it is more understandable
• Polymorphism → data can be used in different form

Disadvantages

• Not widely developed and complete to use it in database system.
• It approach is for solving the requirement. It is not technology. Hence it fails to put the DBMS.

Author Spotlight

Santosh Chapagain
Gmail: chapagainsantoshcs@gmail.com
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