Office Management Tool - II Institute of Management Sciences Muhammad Shahzad AliLec 1: Introduction...

Office Management Tool - II Institute of Management Sciences

Muhammad Shahzad AliLec 1: Introduction to Databases

L E C T U R E

1 INTRODUCTION TO DATABASE MANAGEMENT SYSTEM



The database environment

• To be able to function, an organisation needs information, e.g.

– list of books in a library, – customer details in a retail business, – specifications of cars and their components for a car

manufacturer

• Information may be defined as data represented in a meaningful form.

• Same data shown in different ways will provide different information to different viewers



• A major requirement of any computer system is to store and retrieve data in a way that is meaningful to the end user –

– so the core of any Information System is data, which is to be transformed into information through data modelling.



Definitions

• Data: – Meaningful facts, text, graphics, images, sound, video

segments.

• Database: – An organized collection of logically related data.

• Information: – Data processed to be useful in decision making.



• Metadata:

– Data that describes the properties or characteristics of other data.

– Does not include sample data

– Allows database designers and users to understand the meaning of the data



What is Databases?

• Often abbreviated DB.

• A database is a collection of related information.

• A database is a collection of information that is organized so that it can easily be accessed, managed, and updated.

– For example, a phone book is a database of names, addresses and phone numbers.



• A collection of information organized in such a way that a computer program can quickly select desired pieces of data.

• You can think of a database as an electronic filing system



• Traditional databases are organized by fields, records, and files.

• A field is a single piece of information;

– a record is one complete set of fields; and

– a file is a collection of records.

– For example, a telephone book is similar to a file. – It contains a list of records, each of which consists of

three fields: name, address, and telephone number.



Database Management System (DBMS)

• To access information from a database, you need a database management system (DBMS).

• This is a collection of programs that enables you to enter, organize, and select data in a database.

OR

• A Database Management System (DBMS) is a software tool that facilitates creating, maintaining, and manipulating an information database.



• DMBS is a collection of programs that enables you to store, modify, and extract information from a database.

• There are many different types of DBMSs, ranging from small systems that run on personal computers to huge systems that run on mainframes.

• The following are examples of database applications:

– computerized library systems – automated teller machines – flight reservation systems



• Requests for information from a database are made in the form of a query.

• In fact, most of today's database systems are referred to as a Relational Database Management System (RDBMS), because of their ability to store related data across multiple tables.



Relational Database Management System (RDBMS)

• A relational database management system (RDBMS) is a database management system (DBMS) that is based on the relational model as introduced by E. F. Codd.

• Most popular databases currently in use are based on the relational database model.



• A short definition of an RDBMS is:

– a DBMS in which data is stored in tables and the relationships among the data are also stored in tables.

– The data can be accessed or reassembled in many different ways without having to change the table forms.



Relational Database Management System (RDBMS)

• A relational database management system (RDBMS) is a program that lets you create, update, and administer a relational database.

• Relational Database Management System a type of database management system (DBMS) that stores data in the form of related tables.

• An important feature of relational systems is that a single database can be spread across several tables.



• Some of the more popular relational database management systems include:

– Microsoft Access

– Filemaker

– Microsoft SQL Server

– MySQL

– Oracle



What is Record?

• In the context of a relational database, a row—also called a record or tuple—represents a single, structured data item in a table.

• In simple terms, a database table can be thought of as consisting of rows and columns or fields.

• Each row in a table represents a set of related data, and every row in the table has the same structure.



EMPNO FIRSTNME LASTNAME WORKDEPT JOB

000010 Christine Haas A00 President

000020 Michael Thompson B01 Manager

000120 Sean O'Connell A00 Clerk



What is Entity?

• The first step in developing a database design is to identify the types of data to be stored in database tables.

• A database includes information about the entities in an organization or business, and their relationships to each other.

• In a relational database, entities are represented as tables.



• An entity is a person, object, or concept about which you want to store information.

• Some of the entities described in the sample tables are employees, departments, and projects.

EMPNO FIRSTNME LASTNAME WORKDEPT JOB

000010 Christine Haas A00 President

000020 Michael Thompson B01 Manager

000120 Sean O'Connell A00 Clerk



What is Field/Column?

• Within a relational table, each row of data in the table is a collection of related data values.

• There are characteristics to each piece of data in each row.

• Columns are used to identify and classify each piece of data.

• Each column in a table must have a name that is unique for that table.



• The data type and length specify the type of data and the maximum length that are valid for the column.

• Data types may be chosen from those provided by the database manager or you may choose to create your own user-defined types.



Database Applications

• Banking: all transactions

• Airlines: reservations, schedules

• Universities: registration, grades

• Sales: customers, products, purchases

• Online retailers: order tracking, customized recommendations

• Manufacturing: production, inventory, orders, supply chain

• Human resources: employee records, salaries, tax deductions



Data Manipulation Language (DML)

• Language for accessing and manipulating the data.

• DML also known as query language.

• Structured Query Language (SQL) is the most widely used query language.



Relational Model

Attributes



A Sample Relational Database



Architecture for a Database System



• The DBMS Manages the Interaction Between the End User and the Database.



The Database System Components

• Hardware

– Computer

– Peripherals

• Software

– Operating systems software

– DBMS software

– Applications programs and utilities software



• People

– Systems administrators

– Database administrators (DBAs)

– Database designers

– Systems analysts and programmers

– End users



• Procedures

– Instructions and rules that govern the design and use of the database system

• Data

– Collection of facts stored in the database



Types of Database Systems

• Number of Users

– Single-user

• Desktop database

– Multiuser

• Workgroup database

• Enterprise database



• Location

– Centralized

– Distributed

• Use

– Transactional (Production)

– Decision support

– Data warehouse

Office Management Tool - II Institute of Management Sciences Muhammad Shahzad AliLec 1: Introduction...

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