2. Information Systems
This is the second core topic in the HSC
course i.e. it is compulsory
The syllabus begins with an overview of
various types of information systems.
Some of these systems form the basis of
later option stands. For example:
• Transaction processing systems
• Decision support systems
3. Databases
However, the major emphasis of this
topic is on
“… the process of organising, storing
and retrieving data with database
systems and hypermedia.”
4. Skills for Information systems
For a given example of a database
information system students need to be
able to:
• identify Participants
• identify Data/information
• identify Information technology
• describe the relationship between participants,
data/information and information technology
5. Examples of Information systems
To practice the above skills, the
syllabus suggests applying the
previous skills to some example
database systems:
• School databases
• RTA
• Video store
6. Examples of Information systems
If it can be arranged, these systems can
be visited, with students noting down the
participants, data/information, information
technology and describing the various
relationships
An ‘excursion’ to the school library or to
the administration section of the school is
a cheap and easy (paper-work-wise) way
to accomplish this goal
7. Examples of Information systems
Alternatively, students may be asked
to research the RTA and the local
video shop in their own time
Examples should not be limited to
those given in the syllabus - you or
the students may be able to come up
with something localised or relevant
to their experiences
9. Computer based vs Non-Computer
based
Students often get fixed on the idea that a
computer based solution is always the most
efficient and most appropriate
The telephone book is an example of a non-
computer based information system, that is
efficient and sufficient for 99% of people for 99%
of the time
Compare the length of time it takes to look up a
phone number in a book to the time taken to look
up the same phone number on the internet
Are there any advantages to using the internet
for this task?
10. Computer based methods for
Organising Data
There are three choices
• Flat file systems
• Database Management Systems (to
operate ‘relational’ databases)
• Hypermedia
The work on hypermedia is best held
over until the next topic,
Communication systems or the
Multimedia option
11. Flat File Systems
These systems store data in a single file
The data is divided up into columns (called
fields) and rows (called records)
Data in fields are comprised of characters
and form data of various types:
alphanumeric (‘text’), numeric (including
date, time, currency, etc), boolean (T/F,
Y/N, M/F, etc) and so on
Any of the simpler database programs –
such as that found with Microsoft Works or
AppleWorks create flat file databases
12. Flat File Systems
Key field – this field contains data to uniquely
identify every record in the database
These are also used in relational databases
Flat file databases are perfectly acceptable for
certain situations
They can become inefficient and difficult to
manage for large volumes of data. Why?
e.g. a student’s CD/DVD collection is a useful example
to demonstrate ‘data redundancy’ in a flat-file database
system
13. Database Management Systems
(DBMS)
A DBMS is the software used to
• Create
• Manage, and
• Query
… a database.
A DBMS is used for more complex
organisation of data, like that commonly
used in a relational database
It is not a part of the database - the
database is just the collection of data files
14. How a DBMS Works
Database
D
B
M
S
User
Data Base
Management
System
15. Organisation of Relational
Databases
There are a number of files called tables
(sometimes called entities or relations)
The columns (fields) of each table are
called attributes
The rows (records) are known as tuples
Each table must have a primary key
Tables are linked by having a field in one
table (foreign key) which is a primary key
field in another table
16. Design of relational databases
The purpose of the database will play
the major role in determining:
• How data will be organised in the
database
• How the database will be designed
The process of designing a relational
database is sometimes called
‘Database Modeling’
17. Design of relational databases
An excellent example of how this is done
can be found at
http://hsc.csu.edu.au/ipt/info_systems/2-4/da
Denise Tolhurst steps through the whole
process from the design of the Entity
Relationship Diagram (ERD) through to
the construction of the database tables
I have used this article with my IPT
classes and used dummy data to create
the database
18. Design of relational databases
At this website there is also an
interesting and useful article that
describes the development of a
database in terms of the system
development cycle
This later article has information on
database schema, keys and data
dictionaries
19. Design of relational databases
Page 30 of the syllabus support document
also has an example of a database
schematic diagram
Page 31-32 also has a great example of a
relational database that could be used by
a video store
An interesting exercise is to get the class
to work backward and develop the ERD for
this database, then work forward and
develop the schematic diagram and the
database itself
20. Normalising a database
Getting a clear and unambiguous
definition of Database Normalisation
is very difficult
The ultimate goal of normalisation is
simple: to reduce the amount of
redundant data in a database
How this is done is quite complex
and barely within the ambit of the
syllabus
21. Normalising a database
Powers => “Normalisation is the process
of organising data into tables so that the
results of using the database are
unambiguous and as intended”
Ware, Cheleski & Chivers => “Normalising
a relational database involves linking
attributes directly from the original data
fields and eliminating situations where
attributes are linked to other attributes”
22. Normalising a database
Neither definition is very helpful
I define Normalisation as: “ the
process of organising data into
groups of tables in order to minimise
data redundancy”
NOTE: We can never completely
eliminate redundant data
24. Data Independence
The database and the DBMS are two distinct
entities
As such each may be stored in separate locations
For example, the database itself may be stored
on a database server. The software used to
access the database may be Microsoft Access or
FileMaker Pro that is stored on the user’s
computer
This allows for multiple users to have access the
database simultaneously
It also means that the DBMS may be updated
without effecting the database
25. Retrieving data from the database
The most common way of retrieving
information is using Query By Example
In Access this is done by
• selecting the query button
• selecting the fields you want to search and
display
• Entering a value for a field (criterion)
• Pressing the query button
This is a highly effective method for doing
a search of data
26. Structured Query Language (SQL)
SQL is a more powerful method of
retrieving data from a database
SQL queries are often embedded in
other programming languages e.g.
Cobol
SQL is a programming language in
itself however, for IPT we only need
to know the basics
27. Structured Query Language (SQL)
The four basic SQL statements are:
• SELECT - used to display data fields that
satisfy a given rule
• UPDATE- change a value in a field/s
• DELETE - delete a record from a file
• INSERT – add a new record to the file
28. Structured Query Language (SQL)
SELECT is used to display data fields
that satisfy a given rule
e.g. to search for the phone numbers
and status of all suppliers in Paris we
would use the following
SELECT SupplierPhone, SupplierStatus
FROM tblSupplier.tbl
WHERE SupplierCity = “Paris”;
29. SQL – Wildcards
These are used when a complete value is
not known
! is used to represent a single character
* is used to represent a group of
characters
e.g. SELECT SupplierName
FROM tblSupplier.tbl
WHERE SupplierCity = “*”;
This would list all suppliers
30. Joining Tables
SQL can be used to retrieve data from more than
one table, e.g.
SELECT Surname, City, PartName, Weight
FROM tblSupplier, tblPart
WHERE Supplier.City = “Paris”
This query displays (selects) the fields Surname
and City from the Supplier table and PartName
and Weight from the Part table, on condition that
the Supplier’s City is Paris
31. Displaying Data
There are a number of ways to display
data in a database
We can view the individual data tables,
where we can see all of the records that
make up the table
We can create forms to view individual
records. We can even select which fields
to display
We can create a report that will display
the data in a professional manner
Reports can be made from queries
32. Social and Ethical Issues
There are many social and ethical issues to
consider with this topic
The most important are Privacy, Security and
Control and examples may include ‘identity theft’
and the cross-linking of previously independent
government databases
This has been discussed in earlier lectures
Also see a provocative source of discussion at
http://www.adcritic.com/interactive/view.php?%20id=
Most of the existing texts do a good job covering
these and other related issues
