Post on 25-May-2015
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
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)