Database Management System

Obiective

To make you known about the fundamentals of Database Management System and Improve ourselves by taking valuable feedbacks from you.”

Contents

• Introduction
• What is Data?
• What is Information?
• Database
• Data Models, Schema and Instances
• Componets of Database System
• What is DBMS ?
• Databasc Administrator (DBA)
• Database Languages
• Database System Architectures
• Advantages of DBMS
• Disadvantages of DBMS
• Examples of DBMS
• MS-Access
• Applications of DBMS

Introduction:

• DBMS stands for Database Management System.
• DBMS is a software system for ereating, organizing and managing the database.
• It provides an environment to the user to perform operations on the database for creation, insertion, deletion, updating and retrieval of data.

What is Data ?

• A collection of raw facts and figures.
• Raw material that can be processed by any computing machine.
• A collection of facts from which conclusions may be drawn
• Data can be represented in the form of numbers and words which can be stored in computer’s language. i.e. Paan Singh, Anshul 007

What is Information?

• Systematic and meaningful form of data.
• Knowledge acquired through study or experience.
• Information helps human beings in their decision making.

Database

• Arepository of logically related and similar data.
• An organized collection of related information so tha it can easily be accessed, managed and updated.

Example:
Dictionary,Airline Database,Student Database,Library,Railways Timetable,YouTube (All songs of Rahul Vaidya)

Data Models, Schema and Instances

Data Models:

• Describes structure of the database.
• Aim is to support thc development of informationmat of data. systems by providing the definition and format of data.
• If the same data structure are used to store and access data then different application can share data.

Classification:

1. High Level Model
2. Representation Model
3. Low Level Model

1. High-Level Model

• Ensures data requirement of the users.
• Not concerned with representation, but it’s a conceptual form.
• Three Imp terms:

a)Entity: Any object, exists physically or conceptually.

b)Attributc: Property or characteristic of entity.

c)Relationship: Association or link b/w two entities.

These 3 terms make Entity-Relationship Model.

2. Representation Model

• Representation of data stored inside a database.
• Describes the physical structure of the database.
• It uses the concepts which are close to the end-users.

Classification:

1. Hierarchical
2. Relational
3. Network

a. Hierarchical Database Model

• Developed by IBM, is the Oldest database model.
• Represented using a tree-diagram. (Parent-child relationship)
• Each box is called a ‘Node
• The nodes represent a record type
• A line connecting nodes represents the link.
• Parent-child type is suited for One-to-many relationship between two entities.
• But difficult to implement many-to-many relationship.
• e.g IMS system from IBM.

b. Relational Database Model

• Simplest and the most common model.
• Developed in 1970 by E.F. Codd, it became commercial in the 80s.
• Data elements are stored in different tables made up of rows and columns.

Terminologies:

Data Values:
alphanumeric raw data (Rajkumar)

Columns:
fields (item or object that holds the data)

Rows:
Record (a group of data for related field)

Table:
Collection (all records & fields)

Key:
identifier (uniquely identifies a row in the table. It can be value of a single or multiple column. e.g DB2, ORACLE, SQL Server.

C. Network Database Model

Represented using a Data-Structure Diagram.Boxes represents the records & lines the links.Based on Owner-member relationship.Members of an owner may be many but for many member owner is one.Can represent one-to-one and many-to-many as well.

One-to-many relationship is converted into a set of one-to-one.Also, many-to-many is converted into 2 or moreone-to-many relationship. e.g IDMS, IMAGE.

Schema

• Logical structure of the database.
• Doesn’t show the data in database.

Classification:

1. Physical
2. Conceptual
3. External

1. Physical Schema:

• Describes the physical storage of database.
• Not in terms of blocks or devices, but describes organization of files, access path etc.

2. Conceptual Schema:

• Describes structure of whole database.
• Describes entities their relationships and constraints.

3. External Schema:

• Provides a user’s view of data.
• Shows relevant info particular to user, hides rest of the info.
• one or more levels.

Instances:

Actual data contained in database at a particular point of time.

Components of Database System

1. Users
2. Data
3. Hardware
4. Software

Users:

People who interact with the database:

• Application Programmers.
• End Users.
• Data Administrators.

Software

Lies between the stored data and the users:

• DBMS.
• Application Software.
• User Interface.

Hardware

• Physical device on which database resides. e.g Computers, Disk Drives, Printers, Cables etc.

Data

• Numbers, characters, pictures. e.g. Shri Shri Nilesh, 1008, India.

What is DBMS?

A set of programs to access the interrelated data.DBMS contains information about a particular enterprise.Computerized record keeping system.

Perform operations

• Creation
• Insertion
• Deletion,
• Updating & Retrieval of information

Database Administrator (DBA)

Individual or a group, having centralized control of the database. Has a good understanding of database and coordinates all activities of the database.

Functions:

• Defines schema.
• Defines storage structure and access methu.
• Modification of both.
• Granting user authority to access the database.
• Monitoring performance and responding to changes,

DBMS:

1. Data Definition Language
2. Data Manipulation Language

1. Data Definition Language (DDL):

DDL Used by DB designers to define schema.DDL compiler converts DDL statements and generate a set of tables which are stored in. e.g.: SQL

2. Data Manipulation Language (DML):

For accessing and manipulating the data. e.g.: SQL

3. Data Control Language (DCL)

Similar to a computer programming language used to control access to data stored in a database. operations like:CONNECT, SELECT, INSERT, UPDATE, DELETE, EXECUTE, and USAGE. e.g.: SQL

Database System Architectures

The journey from big mainframe to pc has also evolved the database and its architecture.

Classification:

1. Centralized DBMS Architecture
2. Client-Server Architecture
3. Distributed Databases

1. Centralized DBMS Architecture

Traditional form, all data, functionality, apps are located on one machine.Access via communication links.

2. Client-Server Architecture

Involves a client and a server.Clients are PCs or workstations.Servers are powerful computers, can manage files,printers, e-mails.Client interacts server when additional functionality doesn’t exits in its own machine.

3. Distributed Database Architecture

Decentralized functionality, distributed among many computers.Storage computers are at diff. geographical locations.

Advantages of DBMS

• Controlling Data Redundancy:
  

  Data is recorded in only one place in the database and it is not duplicated.

• Data Consistencv:
  

  Data item appears only once, and the updated value is immediately available to all users.

• Control Over Concurrency:
  

  In a computer file-based system in updating, one may overwrite the values recorded by the other.

• Backup and Recovery Procedures:
  

  automatically create the backup of data and restore data if required.

• Data Independence:
  

  Separation of data structure of database from application program that uses the data is called data independence.

Disadvantage of DBMS

Cost of Hardware and Software:
Processor with high speed of data processing and memory of large size is required.

Cost of Data Conversion:
Very difficult and costly method to conver data of data file into database.

Cost of Staff Training:
A lot of amount for the training of staff to run the DBMS.

Appointing Technical Staff:
Trained technical persons such as database administrator, application programmers, data entry operators etc. are required to handle the DBMS.

Database Damage:
All data is integrated into a single database. if database is damaged due to electric failure or database is corrupted on the storage media,the your value valuable data may be lost forever.

Examples of DBMS

Some of the common used DBMSs are:
Oracle, IBM’s DB2, Microsoft’s SQL Server,MS-Access and Informix.
Some of the desktop based DBMSs are:
Microsoft FoxPro, Borland dBase and Microsoft Access.

MS ACESS(2007,2016,2019,2021)

• Allows creation of database for MS Windows family.
• Permits user to design and create complete database with quick and easy data entry.
• Can store any kind of data: Numbers, pages of text, pictures etc.
• Is a tool for managing the data base.
• It’s a Relational DBMS.

Features of MS-Access 2007

• User can create tables and manage them.
• Can design renorts to nresent the data.
• Attach files to the database.
• It permits filtering the data based on text, numbers and date, and also sorts the data.
• Allows queries to analyze the data.

Applications of DBMS

• Airlines and Railways:
  Online databases for reservation, and displaying the schedule information.
• Banking:
  Customer inquiry, accounts, loans, and other transactions.
• Education:
  Course registration, result, and other information.
• Telecommunications:
  Communication network, telephone numbers,record of calls, for generating monthly bills, etc.
• commerce:
  Business activity such as online shopping, booking of holiday package, consulting a doctor, etc.
• Human resources:
  Organizations use databases for storing information about their employees, salaries, benefits, taxes, and for generating salary checks.

Related Topics

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