Database Management System (DBMS)

What is DBMS?

Database Management System (DBMS) is a software for storing and retrieving users' data while considering appropriate security measures. It consists of a group of programs which manipulate the database. The DBMS accepts the request for data from an application and instructs the operating system to provide the specific data. In large systems, a DBMS helps users and other third-party software to store and retrieve data.

DBMS allows users to create their own databases as per their requirement. The term "DBMS" includes the user of the database and other application programs. It provides an interface between the data and the software application.

Let us see a simple example of a university database. This database is maintaining information concerning students, courses, and grades in a university environment. The database is organized as five files:

• The STUDENT file stores data of each student
• The COURSE file stores contain data on each course.
• The SECTION stores the information about sections in a particular course.
• The GRADE file stores the grades which students receive in the various sections
• The TUTOR file contains information about each professor.

To define a database system:

• We need to specify the structure of the records of each file by defining the different types of data elements to be stored in each record.
• We can also use a coding scheme to represent the values of a data item.
• Basically, your Database will have 5 tables with a foreign key defined amongst the various tables.

History of DBMS

Here, are the important landmarks from the history:

• 1960 - Charles Bachman designed first DBMS system
• 1970 - Codd introduced IBM'S Information Management System (IMS)
• 1976- Peter Chen coined and defined the Entity-relationship model also know as the ER model
• 1980 - Relational Model becomes a widely accepted database component
• 1985- Object-oriented DBMS develops.
• 1990s- Incorporation of object-orientation in relational DBMS.
• 1991- Microsoft ships MS access, a personal DBMS and that displaces all other personal DBMS products.
• 1995: First Internet database applications
• 1997: XML applied to database processing. Many vendors begin to integrate XML into DBMS products.

Types of DBMS

Four Types of DBMS systems are:

• Hierarchical database
• Network database
• Relational database
• Object-Oriented database

Hierarchical DBMS

In a Hierarchical database, model data is organized in a tree-like structure. Data is Stored Hierarchically (top down or bottom up) format. Data is represented using a parent-child relationship. In Hierarchical DBMS parent may have many children, but children have only one parent.

Network Model

The network database model allows each child to have multiple parents. It helps you to address the need to model more complex relationships like as the orders/parts many-to-many relationship. In this model, entities are organized in a graph which can be accessed through several paths.

Relational model

Relational DBMS is the most widely used DBMS model because it is one of the easiest. This model is based on normalizing data in the rows and columns of the tables. Relational model stored in fixed structures and manipulated using SQL.

Object-Oriented Model

In Object-oriented Model data stored in the form of objects. The structure which is called classes which display data within it. It defines a database as a collection of objects which stores both data members values and operations

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