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SUMMARY – Information Systems and Databases Nathan Rees – 2017

Information Systems

Characteristics of Information SystemsOrganisation of Data into Information Data must be organised into information to contain some meaning. Data dictionaries are used to help organise data.

Analysing of Information to Give Knowledge Information is analysed to gain knowledge. Tables, queries and reports are used to help analyse information.

Different Types of / Purposes for Information SystemsTransaction Processing Systems (TPS) Collects, stores, modifies and retrieves transactions of an organisation. Examples: credit card systems, EFTPOS, POS terminals, ATMs. Real-time processing: collects transaction data and processes it immediately. Batch processing: collects transaction data and processes it later as a group of data.

Decision Support Systems (DSS) Assist people with making decisions by providing information, models and analysis tools. Examples: statistical analysis of results/share market/trade figures. “what if” model is used to determine outcomes. Depends on mathematical model and ability of manager to ask suitable questions.

Office Automation Systems (OAS) Provides ways to complete administrative tasks in an organisation. Utilisation of software and communication technology (eg. voicemail, word processors,

spreadsheets, facsimile).

Management Information Systems (MIS) Provides information for the organisation’s managers. Presents basic facts about the performance of the organisation (eg. sales, inventory, payroll,

orders, budgets). Used to motivate workers and make decisions.

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Database Information Systems

School DatabasesEnvironment/Boundaries School community (students, staff, parents) Authorities (NESA, government) Any organisation/individual who receives information generated by the school (textbook

supplier)

Purpose Providing accurate details to each teacher and student with regard to where and what they

should be doing throughout each school day. Enabling the location of any teacher or student to be accurately determined at any time

throughout each school day. Providing flexible retrieval methods so timetable data in various forms can be provided to the

school’s admin system.

Data /Information Information on people, resources, processes Equipment registers, finance & purchase orders, library loans, staff information, timetables,

student marks & grades

Participants Admin office and other staff (eg. librarian) Teachers Head Teachers Principal

Information Technology Computers Barcode readers Printers Data projectors

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Participant

People who carry out or initiate information processes within an information system.


Audio devices (speakers) Various applications (eg. Excel, virus protection)

Information Processes

RMS DatabaseEnvironment/Boundaries Drivers, instructors, examiners Vehicle owners and vehicle inspectors Government departments (NSW Department of Transport) Police and courts All NSW roads and traffic lights

Purpose To maintain accurate records of all license and vehicle registrations within NSW. Assigning demerit points to license holders. Ensuring the privacy of customers’ personal details. Providing information to other government departments.

Data/Information Drivers’ details (contact, payment, driving history, license info, age) Vehicle owner details (rego numbers, payment, inspection records)

Participants Data entry operators Admin staff at offices Inspectors/examiners Police departments

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Level 1 DFD for School Timetable System


Electrical engineers for traffic lights

Information Technology Computers Cameras Barcode scanners Radar/speed detectors Virus protection software

Information Processes Renewing vehicle registrations Editing registration details Issuing new and renewed licenses Issuing license suspension notices

Video Stores Database (eg. Blockbuster)Environment/Boundaries Customers Staff Suppliers Other chain stores Head office

Purpose To keep accurate records of stock (DVDs hired/sold to customers), including customer info. To produce financial and statistical reports to be analysed by store management.

Data/Information Customer details (name, address, payment details, current loans, overdue items) Rental records (in stock, on loan, unique barcode number) Products sold (DVDs, snacks) Rental/sale figures

Participants Staff who scan DVDs to be loaned/bought/returned by customers Staff who authorise orders for new stock Head management generating reports

Information Technology Computers Barcode scanners Cash drawer Printer Specialised video store software EFTPOS machine WAN link to head office (to update new stock)

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Organisation

Non-Computer Based Methods of Organising Telephone Books: subscribers’ surnames are sorted alphabetically. Card Based Applications: recipe cards are sorts into categories (eg. fish, chicken, desserts). Filing Cabinets: files are sorted alphabetically. Dictionaries: words are sorted alphabetically. Reference books: words/topics are sorted alphabetically (eg. encyclopaedia).

Advantages/Disadvantages of Non-Computer Based OrganisingAdvantages Disadvantages

Doesn’t require electric power to obtain information

Easy and inexpensive to organise the data No computer skills required Easier to keep secure/private (can’t be

hacked)

Not easily updated Takes up more physical space Takes more time to search for the required

information Only one person can access at a time Can be easily misplaced

Computer Based Methods of OrganisingFlat File Systems A database with a single table of data stored as a single file. All rows (records) are composed of the same sequence of fields (attributes). Allows you to use and manage ONE database at a time.

Database Management Systems (DBMS) Software applications that allow a database to be created, modified and stored/retrieved (eg.

Microsoft Access).

Hypermedia The storage of information using a set of computers that may contain text, numbers, audio,

video, animation and images (eg. WWW).

Advantages/Disadvantages of Computer Based OrganisingAdvantages Disadvantages

Easily edited/updated Large amounts of virtual storage (ie. on

hard disk, the cloud) Fast retrievals using searches and sorts Greater display options (eg. tables, forms,

reports) Data can be backed up Data can be accessed by several people at a

time Confidential information can be restricted

More easily prone to hackers/theft of information

Data can be wiped in the event of a virus/physical hardware damage

Requires electric power to operate hardware

More expensive to set up and operate (eg. IT and training)

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Logical Organisation of Flat File DatabasesFiles Block of data which is divided into a set of related records.

Records Collection of facts about one specific entry in a database. Organised in rows. Divided into one or more related fields.

Fields Specific category of data in a database. Made up of characters. Organised in columns (attributes).

Key Fields Used to uniquely identify a record in each file. Used to sort and retrieve information. Each key usually holds a unique item that applies to only one record.

Characters Single unit of data used in a database. Smallest unit of data people can use (ie. letters, numbers, symbols).

Logical Organisation of Relational DatabasesSchemasAn organised plan of an entire database, demonstrating how each table is linked to one another. Schemas include: Entities: specific titles which attributes are detailed under (eg. a school has separate entities for

students, teachers and classes in separate tables). Attributes: defined property of an entity (eg. LastName, FirstName and PhoneNo – all being

fields part of flat file databases). Relationships: the way in which entities are related to each other using keys

- One to one: each record in the first entity is related to exactly one record in the second entity (eg. a primary school teacher is assigned to one class; customer purchases a car, being owned by only that customer).

- One to many: each record in the first entity is related to many records in the second entity, but any record in the second entity is only related to one record in the first entity (eg. a high school teacher is assigned to many classes).

- Many to many: each record in the first entity is related to many records in the second entity, and vice-versa.

Tables as the Implementation of Entities Table: the organisation of data into rows and columns. Attribute: the column of a table representing a field. Record: the row of a table.

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Relational Database

A collection of two-dimensional (flat file) tables joined by relationships.

Flat File Database

A single table of data stored as a single file. All rows (records) are composed of the same fields (attributes).


Linking Tables using Primary/Foreign Keys Primary Key: every table within a relational database must have a primary key (PK) that uniquely

identifies a record (eg. StudentID). Foreign Key: a field that contains data matching data from the primary key of another related

table.

Data Modelling Tools for Organising DatabasesData Dictionaries Field name: the name of the field (short and unambiguous) Data type:

- Alphanumeric: letters/numbers/symbols- Numeric: numbers/percentages/decimals- Currency- Date: dd/mm/yyyy- Time: hh/mm- Boolean: yes/no, true/false- Calculation: shows formula in the field

Data format: varies depending on country and personal desires Field size: number of characters allowed in the field Description: explains the contents of the field Example: provides an example of possible content

Schematic Diagrams Showing Relationships Schematic diagram: a graphical tool that helps define a relational database and develop a

schema. Entity-Relationship Diagram (ERD): a graphical method of identifying the entities and showing

the relationships between them. Useful in explaining the database simply to people.

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Normalising Data to Reduce Data Redundancy Involves dividing a database into two or more tables and

defining relationships between data, then deleting data that is no longer required.

Avoids inconsistencies among values. First Normal Form (1NF): removal of repeating attributes

across rows so that each field in a table contains different information. That info should be divided into two tables to be sorted.

Second Normal Form (2NF): removal of repeating attributes across columns so that no field values have the same meaning (eg. if ‘date_of_birth’ field already exists then there should be no ‘birth_year’ field too).

Third Normal Form (3NF): further removal of repeating attributes across columns and rows. It places any fields that don’t relate directly to the PK into another table.

Domain/Key Normal Form (DKNF): a key uniquely identifies each row in a table, being the final level which designers hope to achieve.

Logical Organisation of HypermediaNodes and Links Organisation of hypermedia is based on links and nodes,

where a set of nodes and their various links form a web (the WWW being the most obvious example).

Node: a computer that has the destination link.

Uniform Resource Locators (URL) The address of a file or resource on the web. Protocol: identifies the format and method of transmission to

be used. The most common protocol is the hypertext transfer protocol (ie. “http:”).

Domain name: the address of a specific computer where the resource is located. Each domain name can be replaced by the server’s IP address (eg. http://192.168.1.0).

File path/file name: the full path that leads to the file being retrieved.

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Normalisation

The process of modifying the design of a database to exclude redundant data. Progressively decomposing the design into a sequence of normal forms.

Redundant Data

Unnecessary duplicate data in a database

Hypertext

Bodies of text that are linked in a non-sequential manner. Each block of text contains links to other blocks of text.

Hypermedia

An extension of hypertext to include non-sequential links with other media types, such as image, audio and video.

Typical components of a URL


Metadata (such as HTML tags) Metadata: data that defines or describes other data. HTML tags: a type of metadata, specifying how the text is organised and displayed on a

document.- All tags are enclosed within angles brackets “<” and “>”- The brackets indicate to the web browser that the enclosed text is an instruction

(metadata) rather that text for display- The function specified by the start tag is applied to the text in between the start/end tag

o Example: <title> IPT Notes </title>o This results in the title “IPT Notes” being applied to the tile bar of the browser

Tools for Organising HypermediaStoryboards Storyboarding is a technique of visually representing hypermedia screen displays. Two primary elements:

- Individual screen layoutso Each individual screen layout should clearly show the placement of navigational

items, titles, headings and content.o Notes that describe elements or actions that are unobvious should be made.o The theme design of the page should also be included to provide a realistic

representation of the page.- Navigation map

o Illustrating links between screenso Four commonly used navigation structures:

Linear – sequential design; a predetermined path Non-linear – connecting home page through various other linked pages Hierarchical – top down design; connecting home page to all other

pages Composite – combines aspects of more than one structure

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Software HTML editors: allow users to create HTML web pages without the need to use tags (tags are

inserted automatically by the application).- Adobe Dreamweaver- Microsoft FrontPage- Coffee Cup

Storage and Retrieval

Database Management Systems (DBMS) A software application that allows for the entry, manipulation and storage of data in a database

format. Data is organised into tables, retrieved using queries, viewed in forms and displayed in

printable/summarised reports. Examples:

- Microsoft Access- MySQL- Oracle- dBASE

Role in Handling Access to a Database Providing access to the data within the database by sorting and searching. Utilising a data dictionary to organise data. Showing relationships between entities using schematic diagrams. Changing the definition of the database with ease. Using data validation techniques. Providing security measures to restrict access. Providing information about the performance of the database. Creating back-ups of the database.

Independence of Data The separation of data and its management from the software applications that process the

data. This provides the ability of data and its organisation to be altered without affecting the software

applications that process the data (eg. adding new fields, changing the data type or length). Physical organisation of data: when the operating system determines the way in which the data

is physically organised on the storage medium. Logical organisation of data: how the program identifies the data. The user’s view of the data is

determines by the DBMS.

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Direct and Sequential Access of DataDirect Access Data items are accessed in any order. The required data item can be read or written directly without

accessing/affecting any other data items.

Sequential Access Data items are accessed in a predetermined linear sequence. Each preceding data item must be accessed before the required

data item is accessed. This increases the time taken to access the required data item. Unsuitable for most applications (except for backup). Tape drives (eg. video cassette tapes) are the only widely used

sequential storage devices.

Online and Offline StorageOnline Involves accessing storage devices via a network or over the internet. Storage devices are permanently positioned. Storage is available immediately to connected computers. Usually in the form of hard disk drives.

Offline Involves data stored in a manner that it cannot be accessed until the external storage media is

mounted into a drive. Common examples:

- Magnetic tape- CD- DVD- USB drive

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Centralised and Distributed DatabasesCentralised Database A database that is stored at one central location. All users directly access data through a DBMS server. No synchronisation is required.

Distributed Database A database that acts as a single collection of data but is geographically dispersed among several

different computers at different locations. Can reduce transmission costs. May be difficult to keep a complete view of the database. Data needs to be synchronised across all computers to keep the database current. Two-phased commit: a feature used by a DBMS to ensure each part of the database is ready to

transmit and receive, then performs the transmission.

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An example of a distributed database


Storage MediaHard Disks Data is stored magnetically on precision aluminium or glass platters. The platters have a layer of hard magnetic material into which the data is stored. Each platter is double sided, so two read/write heads are required per platter in the casing. Data is arranged into tracks and sectors:

- Tracks: each platter will consist of about 10,000 tracks, which are laid down as a series of concentric circles.

- Sectors: tracks are split up into 200-500 sectors each, where each sector usually stores 512 bytes.

Optical Disks Based on the reflection of light. Lasers provide light then read the light reflected. Either light is reflected well or poorly, representing a 1 or a 0. Each spiral track is composed of pits and lands that each reflect light differently. CD-ROM: (Compact Disk – Read Only Memory)

- Contain one spiral track- Capable of storing between 650-700MB of data in total- Appropriate for constant data (eg. music)

DVD: (Digital Versatile Disk)- Each track can hold 4.7GB of data- A double-sided disk can contain four tracks- Capable of storing 17GB of data in total- Appropriate for standard definition feature films (ie. up to 576p)

Blu-Ray: - Each layer can hold 25GB of data- A standard double-layered disk is capable of storing 50GB in total- Triple-layered and quadruple-layered disks are available for Blu-ray XL drives- Appropriate for high definition feature films (ie. up to 2160p)

Cartridge and Tape Magnetic tape is encased inside cartridges, ranging from the size of a matchbox to a VHS tape. Extremely cost effective; only costs a few cents per gigabyte. The tape is a long strip of plastic coated in a thin layer of magnetic material. In 2017, IBM and Sony made a palm-sized magnetic tape cartridge that could hold 330TB of

data.

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Securing DataEncryption/ Decryption Encryption:

- Process of encoding data in order to maintain confidentiality and security- Algorithm or encryption key is required to encode data

Decryption: - Process of decoding data back to its original form- Reverse algorithm or decryption key is required to decode and read data

Symmetrical: - Same key is required for encrypting and decrypting- Usually used when the data is being sent across one computer/system so the key is not

required to be shared Asymmetric:

- Requires a public key and a private key for decryption- The public key can be shared- The private key must not be shared at all- Often used when transmitting across multiple computers

Backup Storing/copying data to another permanent storage device. Prevents loss of data in the event that data is lost or damaged at its original location. Full backup: all files are copied, regardless if they are currently existing on the backup device. Partial backup: only files that have been created/modified are copied.

- Incremental: backup of all files that have been created/modified since last full or partial backup

- Differential: backup of all files that have been created/modified since last full backup

Physical Security Measures Physically securing the room in which servers and other system critical devices are located. Access is given only to those users who are authorised.

Usernames and Passwords Can be used to secure individual files or a whole system from unauthorised people. Can be used to assign different levels of access to certain users.

Restricting Access using DBMS Views Access is restricted to particular parts of a database for certain users. Based on usernames and client application.

Record Lock (DBMS) Prevents two users from making changes to the same record at the same time. The first user to access a record locks it from any other user for that editing duration.

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Tools for Database Storage and RetrievalSearching and Sorting Searching: extracting relevant information by comparing each data item against some specified

criteria. Sorting: arranges data into a specified order (eg. alphabetical, numerical, chronological).

Query By Example (QBE) A visual method for specifying a query. No knowledge of SQL is required by the user. An empty record is displayed, then the user enters example data of conditions into each field. The query engine then creates corresponding SQL statements, performs the query and displays

the results.

Structured Query Language (SQL) SELECT: selecting the fields required (“*” means all attributes). FROM: indicates the tables/entities the fields are found. WHERE: search criteria/condition to be met. ORDER BY: sorting format for the retrieved data (eg. ascending).

Example: SELECT FirstName, LastNameFROM EmployeeWHERE Employee.FirstName=“Gertrude”ORDER BY LastName ASC

Example: SELECT *FROM CustomerWHERE Customer.AmountOutstanding>=500ORDER BY AmountOutstanding DESC

Tools for Hypermedia Search and RetrievalFree Text Searching Searching a computer based document or database for characters or words. Search engine searches all words and tries to match criteria words supplied by the user.

Search Engine Indexing: databases of indexed websites (URLs) that can be searched using keywords. Web crawlers: programs that ‘crawl the web’ and facilitate indexing by accessing websites and

gathering information that is then stored in such databases. Search Robots: robots scan the indexed databases for pages that contain the keywords of the

criteria provided by the user, then return a list of URLs to be displayed to the user. Metadata: information about data; indexed databases are an example of metadata.

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Reporting on Data Found in Hypermedia Systems Web browsers Stand-alone applications Media players

Other Information Processes for Database Information Systems

DisplayingReporting on Relevant Information in a Database Provides information to the user. Formatted and organised presentation of information ready for printing (eg. mailing labels,

invoices, receipts, sales summaries etc.). A consistent design is required to make it as simple as possible to comprehend. Data should be grouped into logical categories to make it easy for the user to understand. Grouping is emphasised using:

- Headers- Footers- Borders- Lines- Different fonts- Colours- Page breaks

Constructing Different Views of a Database for Different Purposes Table: used to show the overall view of data. Form: used to enter/view/edit data. Report: used as a summary format and printer friendly design.

Issues Related to Information Systems and Databases

Acknowledgement of Data Sources Source: the person or organisation that develops/creates the data. Copyright Act 1968 (Cth): people are NOT allowed to copy other peoples’ work or creations,

however a specific portion can be used for educational purposes if the work is cited and granted permission by the author.

Freedom of Information Acts Freedom of Information Act 1982 (Cth) and the NSW Freedom of Information Act 1989.

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Both acts allow individuals the right to find out any personal AND non-personal data being kept within government AND non-government databases.

Individuals can request a change if the data is incorrect, however the Act doesn’t cover this.

Privacy Principles Privacy Act 1988 (Cth) and the NSW Privacy and Personal Information Act 1998. Privacy is the right of an individual to control their personal data. Organisations must abide by certain privacy principles, including being able to:

- Explain why personal information is being collected and how it will be used- Provide individuals with access to their records- Correct inaccurate information- Divulge details of other organisations that may be provided with information- Describe to individuals the purpose of holding information- Describe the information held and why it is managed

Quality of DataData must accurately suit the purpose of the information system in order to fulfil user needs.

Accuracy and Reliability of DataData must be kept up to date, correct, free of corruption and protected from theft.

Data IntegrityA measure of how correct and accurately data reflects its source.

Data Validation The process of checking the entry of data to ensure it is of the correct format. Range check: checks that data satisfies a small condition of values (eg. dd/mm/yyyy – only values

from 01-12 would be accepted in ‘mm’). List check: compares data to a set of accepted data (eg. State=NSW would be compared against

a list of states to be validated). Type check: checks whether the data is of the correct format (eg. if the field is numeric, only

numerical characters will be accepted). Check digit: a digit is calculated from a code number, then added to the end of that number as

an extra digit (eg. barcodes may add ‘7’ at the end to confirm it has been checked).

Data Verification The process of checking that the data collected and stored in the database is always correct from

the source of data. This is harder to achieve, as interaction with the source is required. Example: banks have policies in place to make sure that when users move address, they should

ring up the bank and confirm that the data of the address field should be updated.

Data Bias The way in which data is captured, manipulated and interpreted. Machines can capture data with less chance of the data being biased. Humans are more likely to be biased when collecting data.

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Access to Data, Ownership and Control of Data Access to data may be limited to authorised personnel only. By having strict control over data, the will be a lower chance of alteration/destruction of data by

unauthorised people.

Data Matching Cross-linking data across multiple databases provides more accuracy. Individuals have less control over the linked data as it exists in multiple locations.

Current and Emerging TrendsData Warehousing A data warehouse is a database that includes copies of data from each of an organisation’s

operational databases. The data warehouse is used by various systems to analyse the activities of the organisation. Helps to provide evidence to assist decision makers improve the organisation’s performance.

Data Mining The process of discovering non-obvious patterns within large collections of data. The can help an organisation discover previously hidden buying patterns from a particular

customer base. Data mining often takes place on data warehouses. Data mining can predict future behaviour based on past trends.

Online Analytical Processing (OLAP) Provides statistical evidence to organisations to help assist with decision making. Information found from data mining is presented visually, online and as needed. OLAP combines multiple databases into multidimensional structures called data cubes. Data cubes help to drill down on specific details, uncovering new relationships.

Online Transaction Processing (OLTP) Involves databases that allow transactions to be processes immediately by users. Often consists of different database systems communicating to complete a single transaction. OLTP allows real-time transactions to take place over the internet.

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