1

Information Systems &

Databases

2

2.1 Information Systems

Look at Integrated Information Processes

3

Store&

Retrieve

ProcessOrganiseAnalyseC

olle

ctD

isplay

Transmit&

Receive

Participant User

InformationProcesses

CDDisc

Memory

Processor

Sca

nner

Key

boar

dM

icro

phon

e

Printer

Monitor

Speaker

ModemNIC

Partici

pantUser

HardwareI/O

(Internal)

ProcessOrganiseAnalyseIn

put

Output

ExternalI/O

Partici

pantUser

Input&

Output

Understand the Problem

4

Store&

Retrieve

Process

Organise

Analyse

Col

lect

Display

Transmit&

Receive

Enter data into WP

Save docum

ent

Print

Ret

riev

eRerieve &

Fax

Interdependenceof

Information ProcessesWord Processing

Format doc

Spellcheck

Understand the Problem/Make Decision

5

Store&

RetrieveProcess

Organise

Analyse

Col

lect

Display

Transmit&

Receive

Enter data into WP

Save docum

ent

Print

Ret

riev

e

Rerieve &

Fax

Format doc

Spellcheck

WordProcessing

OCRWord

Process PrinterInputText

Outputdocument

Context Diagram

Data Flow Diagram

OCRWord

Process PrinterInputText

Printdocument

UserFolder

Save Retrieve Document

3rd level Data Flow Diagram

OCRCreate

docPrinterInput

TextThreeCopies

Editdoc

Printdoc

Memory

UserFolder

keystrokes sentences

Savedoc

Paragraphs

pagesDraft

Final Draft

Memory

Errors Corrections

CorrectedDraft

OCRCreate

docPrinterInput

TextThreeCopies

Editdoc

Printdoc

UserFolder

Savedoc

Paragraphs

pagesDraft

Final Draft

Detailed level Data Flow Diagram

CorrectedDraft

Design Solution

6

Store&

RetrieveProcess

Organise

Analyse

Col

lect

Display

Transmit&

Receive

Enter data into WP

Save docum

ent

Print

Ret

riev

e

Rerieve &

Fax

Format docSpellcheck

3rd level Data Flow Diagram

OCRCreate

docPrinterInput

TextThreeCopies

Editdoc

Printdoc

Memory

UserFolder

keystrokes sentences

Savedoc

Paragraphs

pagesDraft

Final Draft

Memory

Errors Corrections

CorrectedDraft

Source

ScanOK?

No

Yes

CheckOCR

OCRFile

Scandoc

VDU

SaveInput

EditInput

OCRFile

DraftSaveDraft

Edit/saveDraftDraft

FinalDraft

PrintDocument

FinalDraft

3 copies

HowDisplay?

Print

FaxDocument

FinalDraft

Via type 3 modem

Fax

SystemFlowChart

Design Solution

7

Store&

Retrieve

Process

Organise

Analyse

Col

lect

Display

Transmit&

Receive

Enter data into WP

Save docum

ent

Print

Ret

riev

eRerieve &

Fax

Interdependenceof

Information ProcessesWord Processing

Format doc

Spellcheck

Test & Evaluate

8

Characteristics of an information system

•Organising, or •Analysing

•Sorting•Grouping•Indexing•Summarising•Listing•Tabling

•Synthesis•Hierarchy (priority listing)•Questioning (querying)•Reporting

9

Types of information systems

• Process Transactions– Transaction Processing System (TPS)

• Information about an organisation– Management Information System (MIS)

• Help make decisions– Decision Support Systems (DSS)– Expert System

• Manage information within organisation– Office Automation Systems (OAS)– Multimedia System– Database Management System (DBMS)

10

Comparing Systems

•Type •Purpose •Examples

•TPS •Process Transactions

•Banking; POS; Reservations; Loans

•MIS •Information about an organisation

•Accounting; ordering budgeting; production

•DSS •To help make decisions

•Expert system; data mining; risk analysis; modelling; simulations

•OAS •Office administration

•Personal productivity e.g MS Office; Groupware - email; calendars

11

Representing an information system

Purpose• Who is it for?• Need(s) they have

Information System

PEOPLEParticipants UsersOthers

Data(Input)Information

(Output)

Information Technology

H/WS/W

Comms

Information ProcessesC O A S T/- P D

12

2.2 Database information systems

Examples

13

School Databases

• Represent a School Information System diagrammatically showing:– Purpose– Processes– People (Participants/Users)– Data/Information– Information Technology

• Describe the relationships between the participants, data/information and information technology

14

School Administration Database

• Purpose– The efficient and effective operation of the school

• Processes– Timetabling; staff allocations; take roll; record marks; s

• People (Participants/Users)– Teachers; students; administrators; clerks; assistants; technical

support; gardeners; executive

• Data/Information– Classrooms; subjects; class rolls; equipment; books; timetable;

attendance; marks; names & addresses

• Information Technology– Keyboard, monitor, printer, network, file server– School Administration System; Library system

15

RTA

VehicleInspectors

Cashiers

Managers

RegistrationClerksDrivers

Vehicles

DrivingInspectors

Police

RTASystem

16

RTA ?

Purpose• Who is it for?• Need(s) they have

Information System

Participants & Users

Data/Information

Information Technology

Information Processes

17

Video Store Database

Purpose• Who is it for?• Need(s) they have

Information System

Participants & Users

Data/Information

Information Technology

Information Processes

18

Video Store System

Information ProcessesC: Scan video/card S: save database T: Transfer dataA: Search database A: Update data D: Display information

Participants Data/ InformationManager Member data Technology

Staff Video data H: Personal ComputerUSERS Barcodes H: Barcode reader

Customers S: DatabaseOTHERS Information C: PhoneSuppliers Receipt

19

2.3 Organisational Methods

20

Organising dataNon-computer methods

• Organising is the structuring of data

• Manual type databases– Telephone book– Dictionaries– Recipe card files– Encyclopedia– To do list

21

Advantages & Disadvantagesof computer-based methods of organising data

Advantages• Faster• Data does not have to be in set order (flexible)• Data management is easier• Data exchange possible• Large storageDisadvantages• Need a computer• Training usually required• Security e.g during exchange of data

22

Computer based methodsof organising data

• Flat file systems

• Database management systems

• Hypermedia

23

Flat-file databases

• Data is stored and retrieved from a single Table

• Database file contains multiple records

• Each record contains many fields

• Each field contains data (characters)

• Ability to search the database using data in any field (key field or search field

24

Flat-file database

File

•1

•2

•3 •John

•4

•5Records

Field

25

Database

26

Definitions

•Level •Description •Example •(Vet’s DB)

•File •Block of data •Dogs

•Record •Collection of data about one entity

•Spotty’s

•Field •Specific aspect, data of same type

•Spotty, Bassett, 1998, Y, N, Jan03

•Key field •Data unique to record •Year Born = 1998

•Character •Individual letter or number, etc

•Spotty

27

DBMS

• Data Base Management System• Software package that allows users to

access a database• E.g Microsoft Access; Oracle 8i; Informix;

IBM DB2, SQL Server• The data is stored in a database• DBMS database can have different inherent

structures

28

DataBase Structures

The common database structures

• Single Table– Flat-file

• Multiple Tables– Hierarchical– Network– Relational

29

Hypermedia c.f. Databases

Hypermedia• Many files & types• Many locations

Flat-file DB• One file & type• One location• One ‘table’

DBMS• One file & type• One location• Many tables

Distributed DB• Many files• One file type• Many locations• Many tables• Synchronisation

30

Hierarchical DB Structure

Organises data as a series of levels.

Top down structure (nodes and branches)

Each node can have many branches

Each lower level node (child) is linked to a single higher order node (parent)

31

Network DB Structure

Data organised as series of nodes linked by branches

Each node can have many branches

Low-level node (child) can link to more than one high-level node (parent)

32

Relational DB Structure

Organises data in a series of related tables

Relationships established between the tables to provide a flexible way of storing and accessing the data

33

DB Structures Compared

Hierarchical Network Relational

34

Type of DB KeysDB Key is a field that allows data to be accessed; any

field can be used a a key field• Single key - uses one field• Composite key - a group of two or more keys that can

be used to uniquely identify a record in the database• Primary key - data unique to DB• Secondary key - not necessarily unique (can be a

single key or a composite key• Foreign Key (relational databases) Primary key from

one table used to create relationship with another entity

36

DB Keys

• Name, Address, Gender, Age

• J Smith, 3 River Rd, F, 20

• J Smith, 3 River Rd, M 30

• J Smith, 3 River Rd, M, 50

• J Smith, 16 East St, M, 30

37

Relational Database Schemas

• SCHEMA– Organised plan of the entire database

– Shows how and where data is found

– Describes data and the data’s logical relationships

• DB Schema consists of:– Entities

– Attributes

– Relationships

38

ERD

• Entity-Relationship Diagram

• Graphical method of identifying entities and showing relationships

• A type of Data Modelling Tool•CUSTOMER

•Customer_Number

•Customer_Type

•Customer_Name

•Street

•Suburb

•State

•PETS

•Pet_ID

•Customer_Number

•Pet_Name

•Animal_Type

•Breed

•DOB

Primary Key

Foreign Key

39

DB Definitions

• Entity– Specific thing about which information is

collected e.g a company, a person, a product

• Attribute– Defined property of an entity e.g for a entity

(student) attributes could be Surname, Given Name, DOB, Courses Taken etc

– In a flat-file database an attribute equates to a field

• Relationship

40

Data Dictionary

• Data dictionaries hold METADATA (data about data in the database)

• Used to design & manage the database• Known as a Data Modelling tool• Data Dictionary contains

– Table Name– Attribute Name (Field Name)– Field Data Type– Field Size– Field Description/example (purpose)

41

DB Relationships

• The ways the entities in the database are related– One-to-one– One-to-many– Many-to-one– Many-to-many

42

One-to-one

•CUSTOMER

•Customer_Number

•Customer_Type

•Customer_Name

•Street

•Suburb

•State

•PETS

•Pet_ID

•Customer_Number

•Pet_Name

•Animal_Type

•Breed

•DOB

43

One-to-many

•PETS

•Pet_ID

•Customer_Number

•Pet_Name

•Animal_Type

•Breed

•DOB

•VISIT

•Pet_ID

•Visit_Date

•FollowUp_Date

•Amount

•VISIT

•Pet_ID

•Visit_Date

•FollowUp_Date

•Amount

44

Many-to-many

Repairers

Repairer_IDNameStreetSuburbPostcode

Repairers

Repairer_IDNameStreetSuburbPostcode

Suppliers

Supplier_IDNameStreetSuburbPostcode

Suppliers

Supplier_IDNameStreetSuburbPostcode

Suppliers

Supplier_IDNameStreetSuburbPostcode

45

Flat-file c.f Relational

•Feature •Flat-file DB •Relational DB

•# files •One •One

•# tables •One •Many

•Redundancy •High •Low

•Processing •Simple •Complex

•Relationships •Nil •Yes

46

Which to choose?

• Consider a variety of scenarios

• What factors would influence you decision of choosing either a computer based or non-computer based method organise data?

47

Which database?

• Flat-file for simple tasks, a single entity and when redundancy not an issue

• Relational for complex tasks or where multiple entities are involved

48

Flat-file database

• A relatively simple database system in which each database is contained in a single table.

• In contrast, relational database systems can use multiple tables to store information, and each table can have a different record format.

49

Database Management Systems• 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. Examples of database applications: are

• computerized library systems • automated teller machines • flight reservation systems • computerized parts inventory systems

• The terms relational, network, flat, and hierarchical all refer to the way a DBMS organizes information internally. The internal organization can affect how quickly and flexibly you can extract information.

50

Advantages/DisadvantagesDBMS

ADVANTAGES• Data independence• Reduced data

redundancy• Easier to maintain

data integrity• Easier data security• Economy of scale

DISADVANTAGES• Larger file sizes• Higher cost• More hardware

required• Higher impact of

failure

54

Data Modelling Tools

• Data Modelling: the process of identifying entities, attributes and relationships

• Data Modelling Tools include:– Entity Relationship Diagrams (ERDs)– Data Dictionary

55

Database Normalisation• Process of organising data to minimise data

redundancy• Relates to relational databases only• Involves dividing a database into two or

more tables and defining the relationship between the tables

• Objective: isolate data so that additions, deletions and modifications of a field can be made in juts one table and then propagated through the database via defined relationships

56

‘Zero Normal Form - ZNF’

• Let’s say we want to store some personal bookmarks (URLs) for a number of users

• ZNF: because none of the rules of normalisation have been applied

• If we want more URLs, we would need to add more columns - this means data input screen would need to change everytime we added an extra URL

57

First Normal Form

1. Eliminate repeating groups in individual tables. 2. Create a separate table for each set of related data. 3. Identify each set of related data with a primary key.

4.• We've solved the problem of url field limitation.

• But look at the headache we've now caused ourselves

• Every time we input a new record we've got to duplicate company and user name

• Our database grow much larger than we'd ever want it to

• We could easily begin corrupting our data by misspelling redundant information.

58

Second Normal Form

1. Create separate tables for sets of values that apply to multiple records.

2. Relate these tables with a foreign key.

• We're in much better shape. • But what happens when we want to add another employee of company ABC? Or 200 employees?

• Now we've got company names and addresses duplicating themselves, a situation just rife for introducing errors into our data.

59

Third Normal Form1. Eliminate fields that

do not depend on the key.

• Users and urls tables can grow without unnecessary duplication or corruption of data.

• Most developers will say the Third Normal Form is far enough - and in most cases they would be correct.

• But look at our url fields - do you notice the duplication of data?

60

Fourth Normal Form1. In a many-to-many

relationship, independent entities can not be stored in the same table.

61

Fifth Normal Form

• There is one more form of normalization which is sometimes applied, but it is indeed very esoteric and is in most cases probably not required to get the most functionality out of your data structure or application. It's tenet suggests:

• The benefit of applying this rule ensures you have not created any extraneous columns in your tables, and that all of the table structures you have created are only as large as they need to be. It's good practice to apply this rule, but unless you're dealing with a very large data schema you probably won't need it.

1. The original table must be reconstructed from the tables into which it has been broken down.

62

Data Relationships• One-to-one, one-to-many, and many-to-many.• Look at the users table in the First Normal Form example above. For a

moment let's imagine we put the url fields in a separate table, and every time we input one record into the users table we would input one row into the urls table. We would then have a one-to-one relationship: each row in the users table would have exactly one corresponding row in the urls table. For the purposes of our application this would neither be useful nor normalized.

• Now look at the tables in the Second Normal Form example. Our tables allow one user to have many urls associated with his user record. This is a one-to-many relationship.

• The many-to-many relationship, however, is slightly more complex. Notice in our Third Normal Form example we have one user related to many urls. As mentioned, we want to change that structure to allow many users to be related to many urls, and thus we want a many-to-many relationship. Let's take a look at what that would do to our table structure before we discuss it:

63

Database Keys

• In database management systems, a key is a field that you use to sort data.

• It can also be called a key field , sort key, index, or key word. • For example, if you sort records by age, then the age field is a key.• Most database management systems allow you to have more than

one key so that you can sort records in different ways. • One of the keys is designated the primary key, and must hold a

unique value for each record. • A key field that identifies records in a different table is called a

foreign key.

64

Sorting & Searching

• SORT: ascending (A-Z; 0-9) or descending (Z-A; 9-0)– Multiple sorts

• SEARCH– Query the database using Structured Query

Language (SQL)

65

SQL Syntax

Keyword Source Description Example

SELECT Field(s) What is to be displayed

Surname

FROM Table(s) Tables the fields are to come from

Students

WHERE Operator, data Search criteria Gender=‘F’

ORDER BY Field(s) Orders of display

Surname ASC

[]

66

Operators

Type Operator Description Example

Relational >

<=

Contains

Greater than

Less or equal

Criteria

A>B

A<=B

Contains ‘a”

Logical AND

OR

NOT

Both must be true

Either true

false

A AND B

A OR B

A NOT B

67

Sizing a database - Formal method

• 1) Determine how many fields there are on the schema.• 2) Next determine the datatypes of each of the fields -record the field length • 3) Next, locate information on these datatypes storage requirements.• 4) Identify any Diary fields and fields > 255 characters in length • 5) Add up the byte values for each field's storage requirements.• 6) Calculate for diary fields or fields > 255 characters in length, • 7) Determine if you have any indexes built on any fields in the schema. If so, multiply the value of

the storage length of that fields datatype by 1.5. • 8) Add up all the byte values you determined and recorded in the previous steps. This is the base

value for how much space each ticket or record requires in your database.• 9) Estimate how many tickets a day will be entered into the system. Multiply that number by the

value you got in step 8.• 10) Estimate how many days a year your system will be in production. Use a figure of 200 days for

normal businesses (taking into account holidays, weekends, etc.) or 365 if operating a 24x7 production system. Multiply this by the value you got in step 9.

• 11) Multiply the value in step 10 by 1.2 (this adds 20% to account for system "slop" and other miscellaneous overhead). This value now represents approximately how much disk storage it will take to accomodate this schema's growth for the next year. If you have multiple schemas - you will need to do all the previous calculations for each schema

68

• 1) For every 20 or so fields on a schema use a base value of about 1K per ticket. For example,. if your schema has 60 fields, figure a base of 3K per ticket. If there are any indexed fields, add another 0.5k to the base value.

• 2) If there are large text fields or diary fields on the schema, add up all their lengths, multiply by 1/3 and add this to the base total obtained in step 1. For example, my schema has 60 fields, of which 5 are fields > 255 characters in length. I use a base of 3.5K per ticket (it has some indexes). I add up the lengths of each of the 5 large text fields (10K, 20K, 5K, 13K, 10K - total of 58K) and multiply by 1/3 for a total of about 19.3K. Add this to the base of 3.5K. This gives a value of about 22.8K per ticket or record.

• 3) Now multiply the value you obtained in step 2 by the number of tickets a day you expect to enter into the system.

• 4) Now multiply the value in step 3 by the number of business days per year (200 for normal businesses, 365 for 24x7 shops). This is the ballpark figure for how much disk space your schema will need to store a year's worth of data.

Sizing a database - Quick & Dirty Method

69

References

• www.webopedia.com– Database, databases - normalization

• www.phpbuilder.com/columns/barry20000731.php3– Database Normalization And Design Techniques– Barry Wise (itcn.com)– INT Media Group - 2002

• support.microsoft.com• www.devshed.com

70

2.5 Other Information Processes

DISPLAYING - for database information systems

71

Database Views

• Data in a database can be viewed different ways for different purposes

View Purpose

Form view Record displayed as thought it were on paper. (can be used for delete, edit and add data)

Report view Displays only the information that will be printed.

Query view Shows on the data that answers the question

72

Database Reports

• a program, usually part of a database management system, that extracts information from one or more files and presents the information in a specified format. Most report writers allow you to select records that meet certain conditions and to display selected fields in rows and columns. You can also format data into pie charts, bar charts, and other diagrams. Once you have created a format for a report, you can save the format specifications in a file and continue reusing it for new data.

Typically from a Report Generator

73

Report Design Principles

• Consistency of styles, fonts, formatting

• Clear headings and lables

• Clean, simple page layouts

• Page numbers, dates, version details

74

Database screens

• Design and create screens for interacting with selected parts of a database and justify their appropriateness– Form views

75

Hypermedia/Hypertext

• Hypermedia: a combination of media whose locations are linked electronically to provide an easy way to navigate between information

• Information stored as separate documents (or files)

• Hypertext: a system that allows documents to be cross-linked.

76

Nodes & Links

• Link (Hyperlink) usually indicated by a highlighted item. The author must specify the location of the item.

• Node: If another is the destination of the link, that computer is called a node.

77

Characteristics of Hypermedia

•Characteristic •Definition •Example

•Hypertext •Text with links to other documents

•“Hot Spot”

•Link •Connection between elements

•Hypertext; Image Map

•Node •Location where data is stored

•Server on WWW

•URL •Internet resource address

•http:www…..

•Metadata •Data about data •HTML tags

78

URLs

• Uniform Resource Locator = node

http://www.cambridge.edu.au/IPT/ipthsc.htm

Protocol

WorldWideWeb

Domainname

Country

DirectoryFolder

Webpage

79

Metadata Tags

• Metadata: Data about data

• HTML uses tags to tell the browser how the following data is to be handled

• E.g <H1> Metadata</H1>

80

Software for Hypermedia

• Microsoft Powerpoint and can be used to organise text, graphics and sounds for a presentation

81 Wh

ich

sys

tem

to u

se?

Computer-based systems

Information task

Manual System

Flat-file DB

Relational DBMS

Hypermedia

Appointments Diary

Ideal for personal

use

Ideal for business

use

Too complex for task

Ideal for travellers

Product Catalogue

Ideal for letterbox

drops

Simple lists only

Suitable but generallly

too complex

Ideal for web access

Stock/Inventory

Too slow/ difficult to maintain

Simple lists only

Ideal for complex

tasks

Generally not suted

Personnel Records

Too slow/ difficult to maintain

Simple lists only

Ideal for complex

tasks

Generally not suitable

(privacy/security)

Class marks Test results

Ideal (private &

secure)

Ideal for porocessing

Too complex for task

Generally not suited (except HSC results)

Mail Merging Not suited IdealSuited but

genrally too compolex

Generally not suited

Phone/Address List

Ideal for personal

use

Ideal for larger lists

Suitable but generallly

too complex

Ideal for web access

82

How to decide?

• Simple tasks, small amount of stable data (Manual System)

• Complex tasks, large amount of changing data (Computer-based System)– Basic processing, easy to learn/use, simple structures

(Flat-file database)– Complex processing, complex structures (Relational

Database)– Limited processing, needs wide distribution of data

(Hypermedia)

83

2.4 Storage & Retrieval

84

Data Access MethodsDirect (Random) & sequential

To go from point A to point Z in a sequential-access system, you must pass through all intervening points. In a random-access system, you can jump directly to point Z. Disks are random access media, whereas tapes are sequential access media.

85

Storage

• ON-LINE: data processed under direct control of CPU e.g memory of Direct Access Disk (DAD)

• OFF-LINE: data controlled by the system e.g tape of disk

Device Description Storage method

Capacity Data access

Hard disk Fixed metal or glass platters

Magnetic Gigabytes Direct

CD-ROM, DVD

Plastic disk, metal coating

Optical (laser) 650MB-17GB Direct

Removable cartridge

External metal or plastic disk

Magnetic 100MB-2GB Direct

Tape Thin strip plastic on reels

Magnetic Gigabytes Sequential

86

Distributed databases

• A database that consists of two or more data files located at different sites on a computer network.

• Because the database is distributed, different users can access it without interfering with one another.

• However, the DBMS must periodically synchronize the scattered databases to make sure that they all have consistent data.

87

Encryption & Decryption

• Encryption: The translation of data by a secret code.

• The most effective way to achieve data security.

• To read an encrypted file, you must have access to a secret key or password that enables you to decrypt it.

• Unencrypted data is called plain text ; encrypted data is referred to as cipher text.

• There are two main types of encryption: asymmetric encryption (also called public-key encryption) and symmetric encryption.

88

Symmetric & Asymmetric encryption

• Symmetric encryption: the same key is used to encrypt and decrypt the message.

• Asymmetric: A cryptographic system that uses two keys -- a public key known to everyone and a private or secret key known only to the recipient of the message. When John wants to send a secure message to Jane, he uses Jane's public key to encrypt the message. Jane then uses her private key to decrypt it.

89

Hypermedia - search engines

PRELIMINARY  SEARCHING HINTS

1. Choose a search engine, directory or library in accordance with the kind of search you are doing and the kind of results you are seeking.

2. Consider: Are you looking for a Web site? Information that might be contained within Usenet? Academic articles that may only be retrievable with gopher?

3. Determine your aims: Do you want a specific hard-to-find document on an esoteric subject, or general information on a broader topic? Do you need to search the entire Web, or is what you are seeking likely to be found on a number of sites, or only the most popular sites?

4. In making your choice, determine whether the information you are looking for is likely to be in a page's title or first paragraph, or buried deeper within the document or site.

5. Use a search engine's advanced features, if available, and read the help files if you are unclear about its searching procedure.

SOURCE: http://www.windweaver.com/searchguide.htm#PRELIMINARY

90

SEARCH TERMS AND SYNTAX

1. Enter synonyms, alternate spellings and alternate forms (e.g. dance, dancing, dances) for your search terms.

2. Enter all the singular or unique terms which are likely to be included in the document or site you are seeking.

3. Avoid using very common terms (e.g. Internet, people) which may lead to a preponderance of irrelevant search results.

4. Determine how your search engine uses capitals and plurals, and enter capitalized or plural forms of your search words if appropriate.

5. Use a phrase or proper name if possible to narrow your search and therefore retrieve more relevant results (unless you want a large number of results)

6. Use multiple operators (e.g. AND, NOT) if a search engine allows you to do so. 7. If you receive too many results, refine and improve your search. (After perusing the

results, you may become aware of how to use NOT - e.g. Boston AND hockey AND NOT Bruins)

8. Pay attention to proper spacing and punctuation in your search syntax (i.e. no space when using + means +term not +  term)

9. Words between quotations treated as ‘phrases”

91

Web References

• Use full referencing– Author– Title– Publisher– Publications Date– PLUS– Date referenced– URL!

92

World Wide Web

• Use a search engine to locate data on the World Wide Web

93

How a search engine works

• http://www.howstuffworks.com/search-engine.htm

Type Advantages Disadvantages

“Crawler” Finds more pages

Less ‘dead links’

Less reliable page descriptions

Web directory Better page classification system

More reliable page descriptions

Many ‘dead links’

Fewer pages indexed

94

Web crawler

95

Web Directory

• People create the directory

96

2.6 Issues

Related to information systems and databases

97

Issues in handling data

• Privacy, security and accuracy

• What would be examples of inappropriate use of data in a school web site relating to the above issues?

98

Acknowledgement of data sources

• Use full referencing– Author– Title– Publisher– Publications Date– PLUS– Date referenced– URL!

99

Freedom of Information

In New South Wales, the Freedom of Information Act 1989 gives you the legal right to :

• Obtain access to information held as records by State Government Agencies, a Government Minister, local government and other public bodies;

• Request amendments to records of a personal nature that are inaccurate; and

• Appeal against a decision not to grant access to information or to amend personal records.

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Privacy

• The Privacy and Personal Information Protection Act was passed in 1998 and established the Office of the NSW Privacy Commissioner. The jurisdiction of the Act is generally limited to state and local government agencies.

• the Act introduces a set of privacy standards for the NSW public sector. These standards regulate the way public sector agencies deal with personal information.

101

Data accuracy & reliability

• Data integrity - data should be validated and cross-checked– Check the source of the data– Check data against other sources– Use your own intelligence– Acknowledge bias

102

Data Validation methods

• Range checks (dates, amounts)

• List check (against other known data e.g names)

• Type check (numerical, date, text)

• Check digit

103

Access to data

• Who owns my data? Who should be able to access it?

• Should all information be free and available?

• What about medical and credit data?

104

New Trends

• In the organisation, processing, storage and retrieval of data

• Syllabus refers to:– Data warehousing– Data mining

105

Data Warehouse• A collection of data designed to support

management decision making. Data warehouses contain a wide variety of data that present a coherent picture of business conditions at a single point in time.

• Development of a data warehouse includes development of systems to extract data from operating systems plus installation of a warehouse database system that provides managers flexible access to the data.

• The term data warehousing generally refers to combine many different databases across an entire enterprise.

106

An extra DB!

107

Features of a Data Warehouse

• Strategic data (not operational)

• Temporal data (time periods)

• Summary data

• Read-only

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Data Mining• A hot buzzword for a class of database

applications that look for hidden patterns in a group of data.

• For example, data mining software can help retail companies find customers with common interests.

• The term is commonly misused to describe software that presents data in new ways.

• True data mining software doesn't just change the presentation, but actually discovers previously unknown relationships among the data.

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“Drill Down”• to move from summary information to detailed

data by focusing in on something. • To drill down through a series of folders, for

example, on a desktop means to go through the hierarchy of folders to find a specific file or to click through drop-down menus in a GUI.

• To drill down through a database is to access information by starting with a general category and moving through the hierarchy of field to file to record.

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Activity

• Identify and apply issues of ownership, accuracy, security and privacy of information.

111

Activity

• Discuss issues of access to and control of information

• Validate information retrieved from the Internet

112

Activity

• Design and generate reports from a database

113

Activity

• Summarise, extrapolate and report on data retrieved from the Internet

114

ActivityCreate a Database

• Create a simple relational database from a schematic diagram and data dictionary

• Populate a relational database with data

115

ActivityCreate a Data Dictionary

• Create a data dictionary for a given set of data

116

ActivityDocumentation

• Create documentation, including data modelling, to indicate how a relational database has been used to organise data

117

Construct

• Construct a hypertext document from a storyboard

118

ActivitySchema Changes

• Modify an existing schema to meet a change in user requirements

119

Data Flow Diagram

• Diagrammatically represents the flow of information within an information system

Process

ExternalEntity

DataStore

Data Flow

120

Activity

• Develop DFDs for a Library System

BorrowBook

BookBorrower

BorrowersFile

BorrowerDetails

Acquisitions

Book

OrdersFile

Book Details

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DFD - Video Store System

MovieTimeVideo

Member

VideoDatabase

Card, PIN, cash

Video, receipt

TransactionData

Member dataVideo data

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DFD - Appointment Diary

CheckDiary

Person1

Diary

Request appointment

Enter appointment

DiaryPerson

2

Enter appointment

Confirm appointment

123

Backup & Security

• To copy files to a second medium (a disk or tape) as a precaution in case the first medium fails

• FIREWALL: hardware or software that prevents unauthorised access to a network

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Methods of data backupBackup Description Advantages Disadvantages

Full All data on system is backed up

Quick recovery

All data saved

Longer backup

Differential Only changed data since last full backup

Rapid backup

Minimal space

Recovery requires full backup and one incremental

Incremental Only changed data since last incremental backup

Fastest backup

Minimal space

Longer recovery - need full backup and number of incremental backups

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Design & develop a storyboard

• For each of the following situations, decide the most appropriate storyboard layout.

• Design a set of simple labelled sketches to illustrate– A. A very simple children’s educational

program on desert animals for young children– B. A glossary of medical terms for Doctors (in

alphabetical order).

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Storyboard

• A series of frames, each representing a different action or scene

• Storyboards are used to plan and organise hypermedia projects

• Usually drawn on paper; frequently edited• Contain navigation paths, content

information and graphic concepts• Simple to construct

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Storyboard Layout Options

• Linear

• Hierarchical

• Non-linear

• Combination

e.g “cartoon-like’

e.g simple web pages

e.g complex web site

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Use Software

• Use software that links data, such as:

• HTML editors

• web page creation software or a hypertext package