Transcript Information Systems And Databases

INFORMATION SYSTEMS
AND DATABASES
Information Systems And
Databases
 Information Systems
 Examples Of Database Information Systems
 Basic Data Organization Methods
 Organisation of data in databases
 The Organisation Of Data In Hypermedia Systems
 Storage And Protection
 Data Retrieval
 Other Processes And Issues For Information
Systems
Information Systems
Characteristics of information systems
Types and purposes of information systems
Characteristics Of Information
Systems
 The creation of information and data is called information processing, data
processing (DP) or electronic data processing (EDP).
 Much of this information comes to us after an enormous amount of processing
that organises and analyses huge qualities of data.
 Two things stand out about information systems:
- they organise data into a form that is much more useful – to give information
- They allow information to be analysed – to give knowledge.
 Knowledge comes from the analysis of information (organised data), by seeing
the patterns, trends, or charges in data.
Data: Raw facts
Information: Data organised in a way that gives data meaning
Types And Purposes Of
Information Systems
 In general, information systems belong to one of a few broad types:
 Transaction processing systems (TPS): Any activates and products that re part of the normal
operations of an organisation. Eg: orders, sales, and wages.
 One of their main purposes is to provide the data than other information systems need.
 Management information systems (MIS): Take data from transactions processing systems and
produce business information reports.
 The main purpose of management information system is to assist managers in making decisions
that affect the short-term operation of an organisation, such a changing population levels.
 MIS reports are regularly used to describe the health of a business or organisation.
 Decision support systems (DSS): Take data from transaction processing systems, reports from
management information systems and data from external sources such as census and national
economic trends.
 They produce reports that assist senior management to plan for the future.
 These reports are analytical, they analyse data from a wide variety of sources and allow managers to
make “what if” predictions.
 Office automation systems (OAS): Used to manage vast quintiles of data and information in an
organisation to help improve efficiency.
 Typical OAS tools include word processors, DBMS software, voice mail, and desktop publishers.
 As a result of these and other information systems, the traditional organizational structure of business
has started to change.
Examples Of Database
Information Systems
School data information system
RTA vehicle and driver information
database
School Data Information
System–Part 1

-
Environment:
The school community (students, staff, parents).
The educational services offered by the school.
The flow of information between the school and authorities EG: NSW Board
of Studies and NSW Department of Education and Training.
- Hardware and software.
 Purpose: To maintain the efficient operation of the school, its personnel,
finances, resources and administrative tacks. Also provides information of
student enrolments, subject selections and assessments for both school staff
and educational authorities.
 Data / Information:
- Finance and purchase orders
- Library resources and loans
- Staff information
- Student attendance information
- Timetables and room allocations
School Data Information
System – Part 2
 Participants: School office and library staff – Teachers who add class
information , students who who search library catalogue.
 Processes: data collection-enrolment forms, marking class rolls, fees, library
returns and loans. Data organised and stored – student and staff database,
resources of various finance. Data analysed and processed – class lists, student
reports, financial reports., purchase orders, and overdue book lists. Data
transmitted to or received – BOD or DET.
 Information technology: Keyboard and monitor, barcode readers, class lists,
daily absentee lists, order forms and financial statements. Software: OASIS,
Motorised Markbook, Spreadsheet application software, personal database
software
RTA Vehicle And Driver
Information Database–Part 1


Environment:
all drivers, driving instructors, driver examiners.
Vehicle owners, vehicle inspectors.
RTA services such as registration and licensing.
The flow of information between RTA and the NSW Department of Transport
The police and courts
The hardware and software.
Purpose: To manage the registration all drivers and vehicles to the
government and registration payment requests.
 Data / information:
- driver personnel details, payment details
- Driver license number, licence type and classification, driving history
- Vehicle identification number, make and model
RTA Vehicle And Driver
Information Database-Part 2


Data/information:
vehicle owner details, registration number, payment details
Vehicle inspection record, insurance details
GST records
Participants: Data entry operators, inspectors, counter staff and
administration officers at RTA offices, motor registries and vehicle inspections
stations. Police Department Traffic Branch – driving records and vehicle
registrations.
 Processes: Data collected from registration application forms, license
applications, renewals, vehicle inspections and driving test results.
 Information Technology: Data entry and display terminals, EFTPOS
machines, bar code scanners.
Basic Data Organisation
Methods
Manual organising methods
Computer-based organising methods
Which system to use?
Manual Organising Methods
 Manual methods have been used for organising and processing information.
Examples are: telephone book, address book, diary and appointment books.
 Many people still prefer the manual versions to the electronic ones.
 Advantage of manual systems:
- do not require computer, power supply
- Highly portable
- No special skills to use them
 Disadvantage of manual systems:
- Inflexible layout
- One method of access
- One person can access at a time
 Manual information systems are usually slow when you are trying to locate a
particular data item
Computer-Based
Organising Methods



Offer many advantages over the manual versions in that:
Faster.
Data does not have to be in set order.
Data management is easier.
Data exchanged between applicants over networks.
Disadvantages are:
Data accessed only by computer
Training is required
The exchange of data with other computers creates security and confidentiality issues.
Any software package can store and manage data. Word processors and spreadsheet
programs are examples.
 Software designed to organise data falls into three categories:
- Flat file database management systems
- Relational database management systems
- Hypermedia systems
Computer-Based Organising
Methods - Continued
Flat file database management systems




Manage only one database at a time.
Microsoft Works and Microsoft Outlook are flat file systems.
Personal data management tasks and biasness tasks are ideal for the flat file system.
Relatively simple and easy to use.
Relational database management systems
 Allows you to simultaneously manage and use several separate databases.
 Called rational because it allows you to build relationships between the data in the
different databases.
 Examples of this are: Microsoft assess, FoxPro, Filemaker Pro, Oracle and SAP.
 The systems are much harder to learn than flat file systems, but better at managing
complex data processing tasks.
Hypermedia systems
 Popular method for displaying information over networks and internet. Easy to use and
can operate on any computer system
 It had outgrown its original specifications. Unable to keep up for the demand for newer
features, such as adding data processing capabilities to web pages.
Which System To Use?Methods Of Organising Data
Information task
Manual System
Flat file DBMS
Relational DBMS
Hypermedia
Appointments
diary
Ideal because of high
portability,
accessibility.
Ideal for business
use because of easy
maintenance
Too complex
Ideal for travelers who have
access thought the web.
Store sales or
product
catalogue
Ideal for letterbox
drops, hands outs
Ideal for simple lists
Suitable, generally too
complex
Ideal for access via Web
and e-commerce.
Stock/ inventory
Too slow and
difficult to maintain.
Ideal for simple
lists.
Ideal for larger, more
complex lists.
Generally not suitable
Personnel
records
Too slow, difficult to
maintain.
Ideal for simple lists
Ideal for larger and
more complex lists.
Generally not suitable poor
security, privacy.
Phone and
address list
Ideal for personal
use.
Ideal for larger lists
and business use
Suitable, generally too
complex
Ideal for access via Web.
Class marks and
test results
Ideal of portability,
instant access, has
good privacy,
security.
Ideal for data
processing and to
send data.
Too complex
Generally not suitable to be
used for the fast distribution
of final HSC results.
Mail merging
Not suitable.
Ideal for the task.
Suitable, generally too
complex.
Generally not suitable.
Which System To Use?
 If you need instant access to data in any situation then manual methods will
often be more efficient.
 Manual methods are generally limited to simpler tasks involving small
quantities of data.
 Large quantities of data or the data is quickly changing, then computer-based
methods will be more efficient. They are less convenient or portable.
 Choosing three computer-based methods depends on:
- the data has to be widely distributed but little or no processing will be needed
(Hypermedia)
- There are relationships involving data from more than one database
(Relational DBMS)
- Basic processing operations are needed on a simple to learn and use system
(Flat File)
Organisation Of Data In
Databases
The logical organisation of a flat file
database
The logical organisation of a relational
database
Modelling the data
The Logical Organisation
Of A Flat File Database
 Database- all the data files used by the flat file database management system. In many
flat file database systems the database will contain only a single file.
 File- all the data records managed and saved by the flat file database software. It will
normally contain data on a single theme such as vehicle registration records, video tapes
and DVDs in a video rental store. A file must contain at least one record.
 Record-all the data describing a single entity in the database. An entity is for example:
the title, author, classification number, publisher, data published and loan status.
 Field- the smallest complete data item in a record. A filed will contain data on just one
feature of the entity described by the record. This can be displayed as graphical data.
 Key Field- a field that is used to uniquely identify a record in a database. Must use the
same field as the key field. No two key field can contain identical data.a key field can
have manually entered data and can contain text.
 Character- normally a single display or printable symbol, such as a keyboard symbol.
The Logical Organisation
Of A Relational Database
 A relational database is made by linking two or more databases together. The
same logical structure as a normal flat file database.
 A rational database needs additional items to describe its links and the new
data structures they create.
 DBMS is able to link two parent databases through a common field.DBMS
finds relationship data to fill the common field from both databases each
matching record that is found will form a record in the relationship.
Relationship: a table or file created by joining together data from different databases.
Attribute: A field copied from a parent database. Attributes are the columns in a
relationship table shown in a list view.
Calculated Field: A field that is created by a calculation using data taken from other
fields.
Modeling The Data-The
Data Dictionary
 A data dictionary is a comprehensive description of each field (attribute) in the database.
It contains information about the characteristics of each item entered in the database, such
as the field name, field size, data type and field description.
 Field name is the name of the field. It should be carefully selected to avoid confusion.
Field names should be relatively short but clear and unambiguous.
 Data type (or field type) is the kind of data that can be stored in the field. Each field
stores data in a single data type. Some common data types are text, memo, number,
currency, yes/no and date/time. Logical fields contain the logic values ‘true’ or ‘false’.
 Field size, or width, is the number of characters allowed in each field. It should be limited
to the smallest number of characters likely to be needed, as smaller field sizes let the
database work faster.
 Description specifies the contents of the field. A data dictionary is a fundamental tool in
the development of a database. It consists of metadata, or information about data. It
provides a common ground for people working on a project at the same time. For
example, if people are 48 Core working on different entities, they can refer to the data
dictionary to check whether a particular attribute already exists. This reduces data
redundancy. Data redundancy is the undesirable duplication of data within a database.
Modeling The DataSchematic Diagrams
 Schematic diagrams are graphical tools that help define the database and develop a
schema. A common schematic diagram is called an entity-relationship diagram.
 An entity-relationship diagram (ERD) is a graphical method of identifying the entities
and showing the relationships between them. It helps to determine the data to be
included in and excluded from the database. ERDs force people to have a common
understanding of the database. They are a useful tool to explain the database. There are
numerous notations for ERD.
 Normalisation is the process of organising data into tables so that the results of using
the database are unambiguous and as intended. It is a refinement process that aims to
reduce data redundancy. Normalisation results in a database that is more efficient but
more complex because data is separated into more tables.
 The degree of normalisation has been defined in terms of forms, such as:
- First Norm Form (1NF) - moving data items into separate tables where the data in each
table is a similar type. Each table is given a primary key. 1NF is the basic level of
normalisation and usually corresponds to the definition of a database.
- Domain/key normal form (DKNF) - a key uniquely identifies each row in a table. A
domain is the set of permissible values for each attribute. Enforcing key and domain
restrictions ensures there are no problems when modifying the database. DKNF is a
final level of normalisation that most designers aim to achieve.
The Organisation Of Data
In Hypermedia Systems
The logistical organisation of hypermedia
Data design
The Logistical Organisation
Of Hypermedia
 Hypertext and hypermedia are unstructured. They do not have set hierarchical structures
like records, fields, and attributes. They have relationships between and within files.
 Structures in hypermedia are files and links. Files must be in set data formats, such as
ASCII text, GIF or JPEG images, WAV or MIDI sound files, but are other wise
unstructured. They do not have to be specific data structures inside the files.
 The web is not the only example of a hypermedia system – Adobe acrobat, HyperStudio,
Microsoft, PowerPoint and a variety of other “presentation” style software packages are
hypermedia systems.
Node: a device, such as a computer, connected to a network.
The Logistical Organisation
Of Hypermedia – Part 2
 Each web node consists of:
- an ASCII text file- formatted as an HTML document. Ends in ‘.html’ or ‘.htm’. If file has
links, graphics, or audio.
- One or more graphic files – in GIF or JPEG data formats.
- One or more audio files – in WAV or MIDI data format.
- One or more links to a different paragraph in the same HTML document called an internal
link.
- One or more links to other web nodes – ‘external links’.
 The address, called a Universal Resource Locator or URL, has to be in a specific format
for use on web pages.
 The address is divided into distinct sections:
- Protocol – this identifies the rules that your computer must follow to access the web node
and document.
- DNS Server – this is the name of the computer on the internet. The computer is identified
by numbers, not text.
The Logistical Organisation
Of Hypermedia – Part 3
Folder or subdirectory name – the name of a folder or subdirectory on the
DNS computer where a document is stored.
- Filename – the name of the web document. If no name is given then a default
document will be sent to you.
 HTML document uses metadata top control every aspect of the display on your
screen. The text colours, fronts and justification, the positioning of text and
graphics,the links are controlled by placing HTML tags in the file that builds
the web page.
 Other forms of metadata are used in other hypermedia systems.
-
Data Design
 The skills and knowledge needed to different from those needed to design and populate a
traditional database.
 One of the first steps in Hypermedia design is to create a storyboard. The storyboard
shows the links between the web nodes and the node sequences that are available to the
user.
 It provides an overall summary or model of how the data will be presented.
 Placing the data and metadata into Hypertext can be done in several ways:
- Text editors – A HTML file is just an ASCII text file, can be created using text editors.
Text editors are easy to learn and use and never need to change with HTML.They have no
web tools, you will have to remember all the HTML metadata tags.
- HTML editors – More sophisticated than text editors, most come with all the HTML tags
built in. Come with a WISIWIG viewer or web browser. Come supplied with a toolbox
full of utilities.
- Web Editors – allow web designers to create a web site without having to see or use web
tags. Allow rapid web development and prototyping but produce inefficient metadata that
make it difficult to maintain the website.
Data Design – Part 2
 Which one to use will vary. HTML fans will only use a text editor. Beginners
and novices will use Web editors. Most professionals use a HTML editor for
design work, text editor for minor changes, and web editor for a prototype.
 Hypermedia-based information systems are becoming important tools foe
commerce and business. An electronic ‘store’ can be open for business
continuously.
 To achieve this, a company web sits must be able to exchange data with its:
- product database
- Online ordering system
- Credit authorisation system
 There are now many software solutions available that will provide the
necessary data integration for all levels of business operations.
Storage And Protection
Managing stored data
Data storage
Data security
Managing Stored Data –
Part 1
 The DBMS and the data bases is creates and manages are quite separate.
 The DBMS is one or more software files that control all access by users to the
database. They are independent of each other and can be kept in separate
locations.
 Data independence does not mean that a data base can be successfully loaded
and managed by a completely different DBMS.
 Software manufacturers tend to invent their own data formats for their
databases.
Data independence: means that the DBMS and its database are quite separate from each
other.
Managing Stored Data
- Part 2
 One of the main management tasks of a DBMS is to protect the data base against
unnecessary, accidental and unauthorized changes. These problems include:
- Record locking. It is not usual for more than one user to try to access the same data
record at the same time. Users were to make different changes to that record and then save
it back into the data base, only the last user would succeed. Top prevent this, the DBMS
can lock a record as soon as a user loads it. This prevent others from accessing it until the
record is released.
- Levels of access. Only certain users are allowed to make changes to the database. Users
given a higher level of system access with more powers than other users. Ordinary users
would still access the database but will be prevented from altering records. No record
locking is needed unless one of the authorized higher level users is accessing a record.
- Transaction and master files. A large number of changes to the database each day, it is
normal practice to place all those changes in a temporary transaction file and leave the
original database unaltered. Records that have been changed are kept in the transaction
file, while the unchanged records stay in the master file. The master file is updated at a
later time.
Data Storage – Part 1
 Tend to be small and can usually fit on a floppy disk. Commercial databases
are not as compact and require larger storage such as:
- Hard disks
- Optical media such as CD-ROMs, CD-R, CD-RW and DVD
- Removable cartridges such as SuperStor, Zip and Jaz disks, memory cards
- Tapes such as analogue or digital tapes.
 Optical media is a popular choice because of its low cost and high capacity.
 Tapes, while slow, are still popular for data backup and offsite secure storage.
 Removable memory cards are also popular. As their storage capacity increases
and their price drops, they will become suitable for the distribution of other
forms of information.
Data Storage – Part 2
 The variety of storage devices available of databases allows a number of
options for the organisation and delivery of data to users:
- Direct or sequential data access. Optical discs, removable cartridges and
memory cards are direct access devices. Allow almost instant access to data
located anywhere on the storage media. High speed provided by direct access
devices is an obvious advantage.
- Online or offline storage. Always directly available for use and its fast. Hard
disks are the only media that fully qualify as true online storage because most
hard disks drives are permanently part of the computer system. Databases that
will be in constant use, online storage is the best option.
- Shared or distributed databases. Stored on one computer but is available to
all of the other computers on the network. Single copy of the database, which
makes data management and security much easier. Split between several
computers in the network. Every record in the database is available to every
user on the network. Obviously much more complicated to manage but offers
some major advantages for large network, such as each region being
responsible for its own data.
Data Storage – Some Data
Storage Options
Media
Access
Storage
Advantages For Data
Storage
Hard disks
Direct
Online
Fast, reliable, high
capacity
CD-ROM, DVD
Direct
Offline
Inexpensive, reliable,
highly portable
Jaz, Zip disks
Direct
Offline
Portable, easily
rewritable
Magnetic tape
Sequential
offline
Very inexpensive, high
capacity, portable
Data Security – Protecting
Your Data
 One of the roles of a database administrator is to ensure that regular backup
copies are made of all current databases. An incremental back up process that
creates daily backups according to the following schedule.
 If a system failure occurs, then the database can be rebuilt by loading the last
full backup and then loading the transaction backups.
 As a further security measure, one person will have the responsibility of taking
the daily backups home from the office each day. A data security company can
call to collect them. You can send backups to a warehouse storage facility on
the internet.
 Alternative scheme , called mirroring, offers far better protection. Two or
complete working copies of the database are stored on different systems in
different locations.
 They are kept identical by frequent simultaneous copying. If the active system
fails, then a mirror can immediately take over.
Data Security – Protecting
your Secrets
 Data encryption makes it possible for anyone to create coded messages and
data that are beyond the abilities of any currently known software and
technology to easily read.
 The most widely used digital encryption methods are DES, IDEA, and RSA.
 All encryption methods rely on using a key to change the data into a secure
unreadable form. Both DES and IDEA use the one key for both encryption and
decryption. For DES and IDEA the key must be kept private, known to those
people who must be able to send and read encrypted data.
 RSA introduced the idea of a public encryption f\key, one that did not have to
be kept secret. The public key can only be used to encrypt a message-it cannot
be used to read one. A different private decryption key must be created to
encrypt the message.
 This makes RSA the most secure data encryption system yet invented.
Data Retrieval
Queries
Data Sorting
Structured Queries
Searching Hypermedia Systems
Queries
Query: Is an instruction to locate
certain records in a database. The
instruction is usually written
according to a set of rules called a
query language.
Relational operator: the test that
is to be applied to a particular
field in a database. Relational
operators are usually
mathematical such as EQUALS,
LESS THAN. Can also be
BEGINS WITH, CONTAINS.
Logical Operator: allows two or
more individual queries to be
combine. Logical operators are
mathematical and use the words
AND and OR.
 Data can be extracted from a data base by entering a
query. Used with most flat file DBMS programs usually
have a very simple way of writing a query. Link between
the name of the field to be searched and the sample data
is called a relational operator.
 This locates records in a data base by:
- Looking at the data stored in the named field of a record.
- Comparing what it finds with the test data, using the rule
given in the search phase.
 Simple queries can be joined by logical operators to
make a more complicated question. The operator words
AND and OR are designed to join two or more queries
together. NOT is used to give the reverse of a result.
Sorting: The process of placing data records into a set order based on the
contents of one or more fields.
Data Sorting
 A sort operation by selecting a particular field, the primary field, which would
be used to sort all the database records. Additional fields can also be selected
to sort data records that have identical entries in their primary sort field.
 The sort operation usually caused the most problems and confusion is sorting
text fields. Numbers are treated like letters of the alphabet, they are sorted
according to the computer systems alphabet- ASCII.
Data Sort Options
Data Type
Ascending Order
Descending Order
Text
A to Z: using the ASCII value of each
individual character – ‘100’ will be
placed before ‘2’ because ‘1’ has a
lower ASCII value than ‘2’. E.g.
14/10/2002 before 2/5/1999.
Z to A: using the ASCII value of each
individual character.
Sorting records on a text field can be used to quickly to group records with the same or similar entries for that field.
Numerical
0 to 9: using the numerical value of
the entire data field – ‘2’ will be
placed before ‘100’. E.G. 0.9 before
1.0
9 to 0: using the numerical value of
the entire data field.
Sorting records on a numerical data field can be used to quickly find the largest or smallest data value for that field.
Date/time
Earliest to Latest: using the
chronological order of the dates and
times – 7:15pm 2/5/1999 before 3:45
am 14/10/2002
Latest to Earliest: Using the
chronological order of the dates and
times.
Sorting records on a date/time field can be used to quickly find the earliest/oldest or the latest /youngest enteries for that
field.
SQL (Structured Query Language): Is a standard language used to access
and manipulate data in the databases. It allows much more complicated
operations than a simple Query.
Structured Queries
 Relational DBMS packages usually have a much more supplicated query language – an
SQLSUL instructions will automatically:
- Load a particular database
- Find cretin data records
- Sort them into order on a selected field of fields
- Create a properly formatted report using only selected data fields from those records.
 An SUL instruction can be used to assess a database on another computer.
 An SQL can perform many more tasks than just searching and sorting. An SQL can add
new data records and delete old ones.
 SQL is a lot more complex than simple query language on a flat field information
system. The advantage is that the database and DBMS do not have to be running on the
users computer
Searching Hypermedia Systems





Hypermedia information systems are unstructured compared to
database systems and this can make it harder to find a particular
item of data. Common methods for finding data are:
Free text searching
Search engine
A free text is the same as using the Find command in a word
processor to locate a particular word or phrase in a document. It is
limited to the displayable text in the currently loaded web page.
Search engine is often used to describe a web sit that will give
you a list of web pages that have matched your query. There are
two different types of search engines:
True search engines use software robots that automatically search
the web for new pages and to recheck those they have found
previously.
Web directories are made and run by humans. Data on a web sit
are submitted to them and are listed in the directory. Web
directories will allow you the navigate your way down to find the
subject you are after.
Search
Engine
Finds more
pages for an
entered
search
request.
Less likely
to have
“dead
links”
Relies on
less reliable
or accurate
page
descriptions
Web
Directory
Has a better
page
classificatio
n system.
Usually has
more
reliable
descriptions
of each
page
Has too
many ‘dead
links’
Fewer
pages
indexed
Searching Hypermedia Systems
Designing A Page For Indexing By A Search Engine
 Both search engines and web directories tend to work in a similar way to locate pages in
their database and report the results. The differences are that of page rating or relevance
calculation by the search engine.
Other Processes And Issues
For Information Systems
Database reports
Database form views
Issues related to information systems and
databases
Database reports – Part 1
 DBMS programs have the ability to create neatly presented reports from the
database. Standard data display of rows and columns can be useful for many
purposes, such as checking data values.
 Report generators allow you to create your own custom database reports. Add
your own column headings and change the display format of your data values.
 The text and document layout features in a word processor can also be found
in a DBMS generator .
 A report generator can be used as a photocopying tool for developing the
output formats for a system.
Database reports – Part 2
 To create a report, a layout is designed showing where the different features of
the report are to be placed. These features include:
- Static fields. Items that are not copied from database fields. Many of these
will be entered as text data into the report layout or as serial codes for adding
automatic page numbers and dates. Other examples include the report title,
custom page numbering and dates.
- Dynamic fields. There are fields or attributes taken directly from the database.
They are placed into the report as marketers showing where the real data
values will appear when the report is actually created.
- Calculated fields. These are special field markers that perform calculations
using the data that will be added to the report. These include subtotals,
averages, maximums, and minimums and report totals.
Database Form Views
 Restricted to showing a single record at a time but can be just as flexible in
their layouts as reports.
 A form designer is a standard tool with DBMS that gives you control over the
layout and appearance of a database form. Any fields from the database can be
selected and added to the form, in any position. Enhancements, such as colors,
fonts and graphics can be added to the form.
 A form designer can be used as a photo copying tool for developing the data
input and display screens for a system.
Issues Related To Information System And
Databases – Data Source, Accuracy, And
Completeness
 If data has come from another source, it should be acknowledged EG: The
information contained in these Power Points comes form the Jacaranda IPT
text book.
 Data validation means checking data for errors such as spelling mistakes and
entry errors. The most common method is the ‘double entry’ where the data is
typed in twice and compared by the computer for differences.
 Data Verification involves checking stored data for:
- Accuracy – Data can become corrupted. DBMS can detect the error and fix it.
It is best to make copies and backups.
- Integrity – Databases may contain errors such as incorrect DOB’s, addresses.
Issues Related To Information System And
Databases – Freedom Of Information Act
 These are laws that cover the rights of citizens to access data held about them
by the government and agencies.
 The laws do not allow assess to data held by private organisations.
 One criticism of the laws is that many government agencies are exempt from
the Act.
Issues Related To Information System
And Databases – Privacy Principles
 Most organisations adopt ‘Codes of practice’ to protect the privacy of
individuals data. These are purely voluntary and no punishment is made if
these cades are broken.
 General privacy principles may include:
- No personal data that is keep secret from the public. They must be told how
the data will be used.
- People can inspect and correct the data tha has been stored in the information
systems.
- Authorized personnel from the organisation are allowed to asses the database.
It is the organisation responsibility to guarantee the safety of the information.
Issues Related To Information System And
Databases – Data Access, Ownership And
Control
 We rely on information and communications systems for news and current
affairs.
 Most of the information we see is controlled by a few companies.
 Some people believe that this restricts our freedom to find the truth on an issue
or event.
Issues Related To Information System And
Databases – New Trends In Information
Systems
 Because this changes every year, you have to find the most recent information.
 Look at the rise of Google: as it grows into more than a search engine
 Murdock ‘s Media empire as it starts to control most of the worlds news assets.
Data Mining: Is processes of shifting through and analyzing enormous
quantities of data to discover patterns.
Data Warehousing: A data base of cleaned data and the metadata that
describes it.
Modern Digital Data
Encryption Systems
Method
Key Type
Comments
DES
Private
-DES encryption requires special
hardware.
-High security inside the USA
but only moderate security
elsewhere.
IDEA
Private
-A highly secure and fast
encryption system.
RSA
Public
-The most secure system so far
invented.
-Used by Netscape and Microsoft
Internet Explorer to secure the
posting of credit card details on
the web.
-RSA encryption of long
messages if far too slow for
practical use on Personal
computers