INFORMATION

SYSTEMS

DATABASE MANAGEMENT

(PART 1)

Prepared by: Jan Wong

The Learning Outcome

s

Understand what are DATABASES

Identify the components of a database

Explain why data is important to an organization

Understand file maintenance techniques

File processing System VS Database System

The Keyword

s

• Database

• Data Integrity

• GIGO

• Data Hierarchy

• Data Types

• Validation

• File Processing System

• Database Processing System

• Procedure

• Data Dictionary

• Report Generator

Data & Informatio

n

How are Data and Information Related?

• Example:

Student ID

Data & Informatio

n

What is Data Integrity?

• Degree of which data is correct

Garbage in, Garbage out (GIGO) - cannot create correct information from incorrect data

Data & Informatio

n

What are the qualities of Valuable Information?

• 6 Qualities:

Accurate

Verifiable

Timely

Organized

Meaningful

Cost Effective

• + 1: Accessible

Data & Informatio

n

What is a database?

• Collection of data, organized so you can access, retrieve and use it

Database Software (DBMS)

• Database Management System (e.g. Access, Oracle, MySQL, MS SQL)

Create database

Add, Change (edit) & Delete Data

Sort & Retrieve Data

Create Forms & Reports

DATABASE

Data Hierarch

y

DATABASE

FIELDS

CHARACTERS

FILES

RECORDS

1D

U

F

C

11

In other words…

DATABASE

Data Hierarch

y

What is are fields?

• Combination of one or more characters

• Smallest unit of data a user can access to

• Field Name: Uniquely identifies each field

• Field Size: Defines the maximum number of characters the field can contain

• Data Type: Specifies what kind of data the field contains

FIELDS

Data

Hie

rarch

y:

Data

Types

• Also called AlphaNumeric

• Letters, numbers & special characters

Text

• Numbers onlyNumeric

• Unique number automatically assigned to each new record

AutoNumber

• Currency• Numbers with decimal values

Currency

• Month, day, year and timeDate

• Lengthy alphanumeric entriesMemo

• Also called Boolean• Only for values ‘Yes’ /

‘No’ or ‘True’ / ‘False’Yes/No

• Web address that links to document or web page

Hyperlink

• Also called BLOB (binary large object)

• Photograph, audio, video, or any external file

Object

Data Hierarch

yWhat is are records?

• Group of related fields

• How to uniquely differentiate records?

Primary KeyRECORD

Data Hierarch

y

What is are data files?

• Collection of related records stored on disk

FILE

Member ID

First Name

Last Name

Address State

TP019123 Milton Brewer 22, Jalan Puchong

Selangor

TP011345 Shannon Murray 14, Jalan Subang

Selangor

TP020134 Elena Gupta 1, Jalan TPM

K.L

TP021954 Louelle Drake 48, Jalan Kamuning

K.L

IN-C

LA

SS

AC

TIV

ITY

Get into groups of 5-6

Select an Information System as below:

• Library Management System

• Lecturer Management System

• Ticket Reservation System (e.g. Cinema)

• Inventory Management System (e.g. Hypermarkets)

List down the contents within it’s database

• Files, Records and Fields

Maintaining Data

What is file maintenance?

• Procedures that keep data current / updated

Adding records

When there is new data

Changing / Editing records

Correct incorrect data

Update of old data

Deleting records

When records are no longer needed

Some programs totally deletes record, some merely ‘flags’ them

Maintaining Data

What is Data Validation?

• Process of comparing data with a set of rules to find out if data is correct

• Reduce data entry errors, duplicates and enhance data integrity before program writes data on disk

File Processing System

• Each department has it’s own set of files

• Records in one file may not relate to records in another file

e.g. HR dept & other depts

• Possible weaknesses:

Data redundancy: Same fields / records stored in different files

Isolated data: Data stored in different files therefore difficult to access

DatabaseProcessing System

• Many programs and users can share data in database

• Secures data so only authorized users can access certain data

• Strengths:

Reduced data redundancy

Improved data integrity

Shared data

Faster / Centralized Access

Reduced development time

“Assists organizations / ‘people’ in creating and managing databases”

Database ManagementSystems (DBMS)

“Data Dictionary - Contains data about each file in database and each field within those files”

Database ManagementSystems (DBMS)

“Report Generator - Allows user to design a report on screen, retrieve data into report design, then display or print reports”

Database ManagementSystems (DBMS)

Database Manageme

ntSystems (DBMS)

What is the difference between Backup & Log:

• Backup – Copy of the entire database

• Log – Listing of activities that change database content

DBMS usually logs 3 items:

Before Image

Actual Change

After Image

Questions,

anyone?

Chapter 2:

Database

Management

(Part 2)