Notes on Database Management System

By Vijay Kumar|Updated : March 17th, 2016

Dear Aspirant,

As you know Computer is very important section to get a good score for Bank Exam 2016.Today we are covering the study material on Database Management System,that will help you succeed in the upcoming exam for Bank

Database: A database contains a collection of related items or facts arranged in a specific structure.

DBMS: DBMS is the acronym of Database Management System.It is a collection of interrelated data and a set of programs to access this data in a convenient and efficient way. It controls the organization, storage, retrieval, security and integrity of data in a database.

The information contained in a database is represented on two levels:

  • Data (which is large and is being frequently modified)
  • Structure of data (which is small and stable in time)



Features of Database

  • Faithfulness: The design and implementation should be faithful to the requirements.
  • Avoid Redundancy: This value is important because redundancy.
  • Simplicity: Simplicity requires that the design and implementation avoid introducing more elements than are absolutely necessary.
  • Right kind of element: Attributes are easier to implement but entity sets are relationships are necessary to ensure that the right kind of element is introduced.


Types of Database:

  • Centralized Database: All data is located at a single site.
  • Distributed Database: The database is stored on several computer.
Users of a DBMS
Database Administrator (DBA): DBA takes care of the administrative tasks of DBMS as the name suggests and his major responsibilities are given below.
  • Management of information
  • Liaison with users
  • Enforcing security and integrity rules
  • Database backup and recovery
  • Monitoring database performance

Database designers:

  • Person responsible for preparing external schemas for applications, identifying and integrating user needs into a conceptual (or community or enterprise) schema.

Application programmers:

  • Application programmers write programs to access/insert/update/delete data from/to database by making use of the various database components.

End users:

  • Users who query and update the database through fixed programs (invoked by non-programmer users) e.g., banking.
Advantages of a DBMS :
  • Data independence
  • Reduced data redundancy
  • Increased security
  • Better flexibility
  • Effective data sharing
  • Enforces integrity constraints
  • Enables backup and recovery

Most important term about database:

Fields:- Each piece of  information in the address book is stored in its own location called a field.

Records:- One full set of fields that is all the related information about one person or object is called a record.

Tables:- A complete colleciton of records makes a table.

Levels of Data Abstraction: There are three levels of data abstraction as given below

data abstraction

  • Physical Level: It is lowest level of abstraction and describes how the data are actually stored and complex low level data structures in detail.
  • Logical Level: It is the next higher level of abstraction and describes what data are stored and what relationships exist among those data. At the logical level, each such record is described by a type definition and the interrelationship of these record types is defined as well. Database administrators usually work at this level of abstraction.
  • View Level: It is the highest level of abstraction and describes only part of the entire database and hides the details of the logical level.

          View Level …Defined by User 

Difference between File system & DBMS

File System

  • File system is a collection of data. Any management with the file system, user has to write the procedures
  • File system gives the details of the data representation and Storage of data.
  • In File system storing and retrieving of data cannot be done efficiently.
  • Concurrent access to the data in the file system has many problems like reading the file while other deleting some information, updating some information
  • File system doesn’t provide crash recovery While we are entering some data into the file if System crashes then content of the file is lost.
  • Protecting a file under file system is very difficult.


  • It  is a collection of data and user is not required to write the procedures for managing the database.
  • DBMS provides an abstract view of data that hides the details.
  • It is efficient to use since there are wide varieties of sophisticated techniques to store and retrieve the data.
  • It takes care of Concurrent access using some form of locking.
  • DBMS has crash recovery mechanism, DBMS protects user from the effects of system failures.
  • DBMS has a good protection mechanism.

Working with a Database:

The DBMS interface presents the user with data and the tools required to work with the data.

  • Creating tables: The first step in building any database is to create one or more tables. As we know tables hold the raw data that the DBMS will work with.
  • Entering and editing data: It allows you to create or edit a data entry form.
  • viewing data: The way data appears on screen contributes to how well users can work with it.
  • Querying the database: A query is a more powerful type of filter that can gather information from multiple tables in a relational database.
  • Sorting records: Sorting arranges records according to the contents of one or more fields.
  • Generating reports: A report is printed information that, like a query result, is assembled by gathering data based on user supplied criteria.                           
Schema: A schema is also known as database schema. It is a logical design of the database and a database instance is a snapshot of the data in the database at a given instant of time. A relational schema consists of a list of attributes and their corresponding domains.

Types of Schemas: It can be classified into three parts, according to the levels of abstraction.

  • Physical/Internal Schema: Describes the database design at the physical level.
  • Logical/Conceptual Schema/Community User View: Describes the database design at the logical level.
  • Sub-schemas /View/External Schema: Describes different views of the database views may be queried combined in queries with base relations, used to define other views in general not updated freely.




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