information systems and databases Flashcards
1
Q
what are the characteristics of an information system
A
- the characteristics of an information system, namely:
- the organisation of data into information: data needs to be organised before it can become meaningful information. organising may require sorting, summarising or classifying before it is stored. a data dictionary is a tool used to help organise the data
- the analysing of information to give knowledge: the information must be analysed so that people can gain knowledge from the information stored. tools used for analysing data includes tables, queries and reports
2
Q
what are some of the different types of information systems
A
include systems used to:
- process transactions
- provide users with information about an organisation
- help decision-making
- manage information used within an organisation
3
Q
what is a transaction processing system (TPS)
A
a transaction processing system (TPS) collects, stores, modified and retrieves the daily transactions of an organisation. examples of these systems are credit card payments, EFTPOS and ATMs. There are two types of transaction processing: batch processing and real-time processing
- batch processing collects the transaction data and processes it later
- in real-time processing, each transaction is processed immediately
4
Q
what is a management information system (MIS)
A
Management information system (MIS).this system provides information about the performance of an organisation to the managers. this involved the production of reports on sales, inventory, payroll, orders and budgets. this measure of performance is used to motivate workers and make decisions
5
Q
what is a decision support system (DSS)
A
a decision support system (DSS) assists people to make decisions by providing information, models and analysis tools. these systems are used in the statistical analysis of examination results, analysis of the stock market for buying and selling shares, and decisions made by a company used a what-if model in a spreadsheet to project future sales. expert systems are examples of decision support systems where a user is asked a set of questions and the answers compared to a knowledge base to obtain a possible solution. doctors use expert systems to determine the correct treatment of a particular disease by comparing signs and symptoms to the knowledge base.
6
Q
what is an office automated system (OAS)
A
Office automated system (OAS). this system provides an effective way to complete tasks in an organisation. a range of appropriate software tools are available for the editing and production of high quality documents and to provide both internal and external communication
7
Q
what is the environment in a school database that holds information on teachers, subjects, classrooms and students (talk about 6 types of environment)
A
- Physical: The school network; part of Department of Education and NESA; where to save documents; who has access
- Social: Needs to be used by students, teachers and administration staff
- Technological: Network access required; will it be available online via the Internet; will there be training to use the system
- Economic: What software can the school afford?
- Political: Can be influences by political parties on the education system overall but not really the specific timetable system
- Legal: Requirements for hours studied on courses; privacy laws about student data
8
Q
what is the purpose of the school timetable system
A
- The purpose of a school timetable system is to:
- Provide accurate details to each teacher and student with regard to where and what they should be doing throughout each school day
- Enable the location of any teacher or student to be accurately determined at any time throughout each school day
- Provide flexible retrieval methods so timetable data in various forms can be provided to the school’s administration system
9
Q
what data/information is used in the school timetable system
A
- data
- Student details such as student number, name
- Subject names
- Classroom details – number, how many students fit into room, is it meant for special subjects
- Teacher names
- Subjects that teachers can teach
- information
- The timetable for each student and teacher
- Results of a search for where to find a student or teacher
- Timetables for rooms – which rooms are available if you want to book a room
10
Q
who are the participants of the school timetable system
A
- Office staff, teachers
- There is a team of teachers who develop the timetable using the software and student subject choices – they are the participants
- If students contribute to the system by making subject choices online, they can be considered as participants as well as users
11
Q
who are the users of the school timetable system
A
Students, teachers, parents and the administration staff are users of a timetable system
12
Q
what information technology is used in the school timetable system
A
- Hardware:
- File servers to store the data
- Laptops and desktop computers
- Network devices
- Screens
- Printers
- Software:
- Specific software to generate the timetable – for us it is Edval
- Also connects to overall school administration system – for us it is Sentral
- Databases are involved in both pieces of software
13
Q
identify the 7 information processes in the school timetable system
A
- Collecting
- Student data is collected – names, numbers, year group. For the timetable system, the data is collected from the overall school administration system
- Student subject choices are collected * Teacher data is collected – names, what they can teach, preferences for classes
- Room data is collected – number of room, how many students can fit in the room, is it a science lab or art room or computer room, etc
- Organising
- Data is organised into a database
- Database schema is developed which represents the tables to be used and their relationships
- Analysing
- Creating the timetable by analysing subject choices, available teachers, etc
- Searching for student location, available rooms, etc
- Creating class lists
- Processing
- Making any changes to the timetable
- Making changes to student details
- Transmitting and receiving
- Sharing the timetable online with teachers, students and parents
- Sharing the data with Department of Education if required
- Displaying
- Viewing the timetable on screens or printing it out
- Viewing the results of searches for the location of teachers or students
14
Q
outline an ISC diagram for the Roads and Traffic Authority system holding information on automobiles and holders of drivers licences
A
- Environment:
- NSW vehicle owners, government (NSW department of transport), police and courts.
- Purpose:
- To manage registration of all drivers and motor vehicles in NSW.
- To provide information to drivers/applicants on matters such as licensing, vehicle registration, etc. as well as statistical information to government and other authorities.
- Data/information:
- Drivers’ details (contact, payment, driving history, license information), vehicle details (registration numbers, make of car, etc.)
- Participants:
- Data entry operators, administration staff at offices, police department
- Information technology:
- Hardware: Computers, cameras, barcode scanners, networking between computers
- Software: Operating system, database software
- Information processes:
- Cover the seven processes; collecting, organising, analysing, storing and retrieving, processing, transmitting and receiving, displaying
15
Q
outline an ISC diagram for a video store holding information on borrowers and videos
A
- Environment:
- Staff, customers around the area, suppliers, other chain stores, head office.
- Purpose:
- Allowing customers to hire videos for a period of time, keeping an accurate record of rentals and stock.
- Data/Information:
- Customer details, current loans and overdue items, rental records (in stock/on loan), rental fees, video details, barcodes, receipts
- Participants:
- Staff, head management
- Information technology:
- Hardware: Computers, barcode scanners
- Software: Operating system, database software
- Information processes:
- Cover the seven processes; collecting, organising, analysing, storing and retrieving, processing, transmitting and receiving, displaying
16
Q
what are some non-computer methods for organising
A
- telephone books where the subscriber’s surnames are sorted alphabetically
- card based applications
- recipe cards
- dictionary - words are sorted alphabetically
- photography album, photos are organised chronologically
17
Q
what are some computer based method for organising
A
- flat-file system
- database management system
- hypermedia
18
Q
what is a flat-file system
A
- A single table of data stored as a single file. All rows (records) are composed of the same sequence of fields (attributes)
- Telephone books, appointment diaries and even filing cabinet
19
Q
what is a database management system
A
- System software for creating and managing databases.
- Data is organised into tables, viewed in forms, retrieved using queries and displayed in reports
- Manipulates the data in different ways, such as sorting and searching
- Allows simultaneous management and use of several separate databases
- Allows relationships between data in different databases (relational databases)
- Data can be organised into different databases for each category and can then be linked together
- Can make flat file and relational databases
20
Q
what is hypermedia
A
- A combination of media whose locations are linked to provide an easy way to navigate between the documents
- World Wide Web is one large hypermedia data store where web pages are linked together
- Mainly used on the Internet
- Limited data processing capabilities
- Allows documents to be cross-linked in such a way that the user can move from one document to another by clicking on a text link (hyperlink)
21
Q
what are some advantages fo computer based organisation methods
A
- data can be easily edited without having to retype all the data
- large storage space is available on disk and data is easily retrieved when required. non-computer databases require a large storage space
- data can be searched for and retrieved quickly
- data can be presented in many formats such as tables, forms or reports
- data can be accessed by several people at the same time
- backup storage can be kept, eliminating the risk of data loss
- access to confidential data can be restricted
- sorting of data is flexible over a range of fields
- arithmetic manipulation of data is possible
- They are considerably faster to search
- the data can be easily exchanged between applications and over networks
- Vast amounts of data can be stored in relatively small amounts of space
22
Q
what are some disadvantages of computer based organisation methods
A
- reliance on technology - consequences from technological failure
- maintenance and upkeep - cost
- digital divide
- The data can only be accessed if you have a computer and then you might also need to have the specific software installed on your computer
- Training is usually required
- The exchange of data with other computers creates problems of security and confidentiality
23
Q
what are some advantages of non-computer based organisation methods
A
- Do not require a computer, a power supply or batteries
- May be portable, weight very little and fit inside a briefcase or bag
- No special skills or training are needed to use them
- A small amount of data can be quickly and easily retrieved and no extensive processing is needed
- No expensive hardware or software is required to be purchased
- Non-computer storage may be more secure because it can be held in locked drawers or offices and is not accessible across a network
24
Q
what are some disadvantages of non-computer based organisation methods
A
- May be physically destroyed by fire, water damage or pests
- If they are very large they may take a long time to search for specific data
- If items are incorrectly filed they may be very difficult to find
- May require more work to display the retrieved information
- Access is usually by one method only, for example, alphabetically by surname or chronologically by date
- Usually only one person can access the data at any one time
25
what are some advantages and disadvantages of flat-file databases
flat-file databases are simple to create and organise, easy to use and inexpensive. however they can have a high level of data redundancy, are slower to access and may have inconsistencies in their report generation.
26
what are the parts of a flat-file database
- files: a collection of related records. the information is stored in the file in such a way that the computer can read information from the file or write information to the file
- records: a collection of related data items, which occur in fields
- fields, key fields
- field - a collection of related data entries. each record is subdivided into fields, where a field is a set of contiguous characters with a special meaning
- key field (or primary key) - a field which uniquely identifies a specific record
- characters
- entry - characters entered into the field
27
what do relational databases do
a relational database organises data used a series of related table. it can be presented in a schema (IS RELATIONAL DATABASE IS NTO NECESSARILY A SCHEMA) or table
28
what is a schema
an organised plan of the entire database, showing where the data is found and the logical relationships
29
what are the parts of a schema
- entities: the specific ‘thing’ about which data is collected and stored. separate table in the schema indicate the entities, for example, customers, salespersons, and so on
- attributes: the defined property of an entity. attributes are the same as fields in a flat-file database. for example first name, date ordered, so on
- relationships: the way in which entities are related to each other. the key field is used to link entities.
- one to one: (seldom used)each record in the first entity is related to exactly one record in the second entity. for example, each primary school teacher is assigned to one class in primary school
- one to many: (often used) each record in the first entity relates to many records in the second entity. for example, each secondary teacher is assigned to many classes in the high school
- many to many: each record in the first entity relates to many records in the second entity, and each record in the second entity is related to many records in the first entity. for example, each student studies many subjects and many students study each subject
30
what are the parts of a table for a relational database
a table is made for each entity (ie each table in a schema can be expanded on in a flat-file table).
- attributes: information in a column (field) of the table is the attribute of the entity and represents the field
- records: a row in the table is called a tuple of an entity and represents a record (its like the name of a person and all their information that relates to that entity)
view image in notes
31
what is a primary key and foreign key
primary key - a field that stores data that uniquely identifies the record
foreign key - an attribute which is the primary key for another table
32
what is referential integrity
Referential integrity is ensured when each foreign key always matches a related primary key. Two issues result from enforced referential integrity that need to be resolved – what to do if a primary key is updated (changed) and what to do if a primary key record is deleted when related records exist?
33
in a relational database, what different user view may be used and for what purpose would each view be used
data can be viewed for different purposes using a variety of formats. these include:
- table view - all the records are displayed in a table format. images are not displayed in this format. used to view inputted data
- form view - each record is displayed separately. the form is used for the input of data into a new record or displaying images that are stored in a field as well as other fields that are stored. commonly used for data input to enter, view and edit data
- report view - output of data for printing. the report can be formatted to have headers and footers a title and logos so that a hard copy can be produced. the report can include information from a query or table and is used to present data retrieved from one or more records. used as a summary format and output of data for printing.
34
what is a data dictionary
contains information abut how the data in each field is to be constructed. a data dictionary contains metadata, or information about data. the description helps to standardise data entry and provide documentation for the database.
35
what is included in a data dictionary ? expand on each
- field name: Name of each field as it appears in a database
- data type: type of data to be inputted. there are 6 types
- data format: shows how the data is to be displayed such as how the date is to be displayed (DD/MM/YYYY) or the number of decimal places in a number (nnn.nn)
- field size or width: the number of characters allowed in the field. the field size can be used to determine the storage space required for the database. if field sizes are kept to a reasonable size, the database will work more efficiently
- description: specifies the content of the field
- example: an example of data is given to illustrate possible valid content
36
what are the 6 different data types that can be entered into a field
- alphanumeric data or text - composed of letters of the alphabet and umbers and can also include symbols from the keyboard. it can also be referred to as text (limited number of characters, access restricted to 50) or memo (greater than 50 characters, presented in a scroll box)
- Unicode or ASCII? Unicode is an extension of the ASCII character set to include many foreign language characters and a variety of other special symbols.
- numeric data - data composed of numbers and numerically-related symbols. numeric data can be formatted to currency or a fixed number of decimal places or percentage
- boolean or logical data - composed of true/false or yes/no
- date data - often displayed as dd/mm/yy or mm/dd/yy
- time data - usually in the form hh/mm eg 11.05am
- calculation - which shows the formula used in the field
37
what are schematic diagrams
schematic diagrams are graphical tools that are used to describe the database and help in the development of a relational database. they identify the entities and show the relationships between them. they help to identify what data is included or excluded from an entity (different to schema)
38
what is normalisation? what might cause unnormalised data
Normalisation is the process of removing redundancies in the tables and fields to produce a set of tables which are flexible and easier to maintain. Normalisation does lead to more tables and relationships but the advantage of normalising a database to Third Normal Form (3NF) is that it improves data integrity and reduces the possibility of anomalies occurring in the data. Anomalies in unnormalised table structures are caused by:
- insertion – data being added may not be consistent with data already in the table relating to the same facts
- Deletion – when data is repeated only some of the data may be deleted, leaving records in the database which should not be there
- Updating – if data is repeated, the update routine might only update some of the records causing inconsistencies between records about the same facts
39
what are the 3 normal forms. how do
- first normal form (1NF).
- Each field stores single data items
- eliminates repeating groups (eg first last name split)
- logical input of data (eg offences split)
- second normal form (2NF)
- table must be in 1NF and every non-key attribute (field) should be dependent on the tables primary key - split into more than one entity, all attributes related to the primary key
- redundant information removed (eg date of birth and birth year)
- third normal form (3NF)
- table must be in 2NF and every non-key attribute is dependent only on the primary key of the table and is not dependent on another attribute in the table.
- if attributes do not contribute to a description of a key, remove them to a separate table
- might be meticulous in making tables (eg seperate table for address as postcode is dependent on the suburb)
40
what is hypermedia
hypermedia is the storage of information using a set of documents or nodes that may contain text, numbers, images, audio and video. each document or node is independent and can be retrieved electronically using hypertext.
41
what is hypertext
hypertext is a system where documents can be cross-linked in such a way that you can navigate from one document to the next by clicking on hyperlinks, which are electronic connections. a well-known application of hypermedia and hypertext is the world wide web. each document (or page or node) is accessed by its URL
42
what are nodes
- a point where links are connected
- any system or device connected to a network that can send, receive, or forward information
- in hypertext terms, some block of information - perhaps a web page, video etc
43
what are links/hyperlinks
- links are embedded with in a node and is taken to another node
- allows the electronic connection to another document or page
44
what is a URL. what are the parts of a URL
a URL (Uniform Resource Locator) is the address of the file or resource on the web. URLs must be complete and exact in order to find the file. An example of a URL is https://www.coles.com.au/catalogues-and-specials . There are 3 parts to the URL
- Protocol - this indicates the particular type of resource. https:// (Hypertext Transfer Protocol) allows access to web pages based on hypertext. ftp:// (File Transfer Protocol) allows files to be transferred between computers on the internet
- Domain name - this is the address of the specific computer where the resource is located. For example, www.coles.com.au
- File path - this is the full path to the file to be retrieved. The domain name and file path is separated by a forward slash, for example /catalogues-and-specials.
45
what is metadata? what is an example of metadata in HTML
metadata is data that describes other data. HTML documents use metadata (HTML tags) to describe the content and layout of a webpage. (when writing HTML code, < > go around a tag. eg 
, )
46
what are storyboards
a storyboard is a frame-by-frame plan for the website. it should include the navigation paths (navigational sequence) the images to be used ad the information to be presented. a well constructed storyboard will act as a set of directions for the construction of the project.
47
what are the four different formats for a storyboard (expand on them)
- linear - this allows the user to move through each page in a sequential fashion. forward and back buttons are used to move between pages
- Forces the user through a particular sequence of nodes
- Useful for training where the content of each node requires knowledge obtained from previous nodes
- Making online purchases
- hierarchical - a number of choices are presented at the beginning and these lead down through other choices. the information is still presented sequentially but the user has more control over how to navigate through it, and can restrict their view to one path
- Sequential path in a top-down design - user moves down through the website finding more and more info
- Suited to information that falls into categories and sub-categories (Government sites)
- non-linear - the user can choose the path of navigation without restriction. there is no particular structure to the presentation of information and it is easy for users to ‘get lost’
- Allows maximum flexibility of design, but users can get lost in a maze of screens
- E.g: Games with multiple endings
- composite - aspects of these three methods are used. this method ensures that the user is given all necessary information and understands pathways, but still has the freedom to control the use of the product. the movements through some parts of the presentation may be linear or hierarchical, but non-linear in other parts
48
what are some software that links data
software that links data includes:
- Hypertext Markup Language (HTML) is a set of special instructions that indicate how parts of a document are toe be displayed and navigated. HTML file are text files that contain HTML instructions or tags. HTML documents are viewed in a web browser. HTML editors are software programs that specialise in producing HTML code. HTML tags are the instructions or metadata. A tag consists of a left-angle bracket (<), a tag name and a right-angle bracket (>). They are usually in pairs to indicate the start and end of a tag instruction. Links are achieved using a hypertext-related tag
- Web page creation software such as dreamweaver and notepad allows for the creation of web pages without having to use HTML> the required HTML tags are inserted automatically by the software and the generated web pages can be viewed in HTML form or as seen on the web browser.
49
when are flat-file databases typically used
A flat-file database is typically used when the data is simple, small in scale, and does not require complex relationships between entities. It is suitable for situations where data is stored in a single table or a series of tables with minimal or no relationships. Flat-file databases are easier to set up and manage compared to relational databases. They are commonly used for small-scale applications, such as personal address books, simple inventory systems, or basic data logging.
50
when are relational databases typically used
a relational database is preferred when dealing with complex and interconnected data that requires efficient management and retrieval. Relational databases excel in handling large volumes of data with complex relationships. They enable the establishment of relationships between tables through keys, allowing for powerful querying capabilities and data integrity enforcement. Relational databases are widely used in various industries and applications, such as e-commerce, banking, customer relationship management (CRM), and enterprise resource planning (ERP) systems, where data organisation, integrity, and scalability are crucial.
51
what are some similarities between flat-file and relational databases
- Data Storage: Both flat-file and relational databases are used to store and manage data.
- Data Retrieval: Both types of databases allow data to be retrieved, queried, and manipulated.
52
what are some differences between flat-file and relational databases
- Data Organisation: In a flat-file database, data is typically stored in a single table or multiple tables without establishing explicit relationships between them. In a relational database, data is organised into multiple tables with established relationships using keys
- Complexity: Flat-file databases are simpler and easier to set up and manage compared to relational databases, which require more advanced knowledge and skills for design, normalisation, and querying
- Scalability: Relational databases are more scalable as they allow for the management of large volumes of data with complex relationships. Flat-file databases may struggle to handle significant amounts of data efficiently
- Data Redundancy: Flat-file databases may suffer from data redundancy as information is often repeated across multiple tables. Relational databases employ normalisation techniques to minimise redundancy and ensure data consistency
- Querying Capabilities: Relational databases offer more sophisticated querying capabilities, including the ability to perform complex join operations, filtering, and aggregation across multiple tables. Flat-file databases may have limited querying capabilities, typically based on simple table lookups
- Flexibility: Relational databases offer greater flexibility as they can adapt to changing data requirements or new relationships by modifying the schema and table structure. Flat-file databases can be less flexible, requiring significant changes to the structure or data format to accommodate modifications.
53
what is a database management system
a database management system (DBMS) is a software application that allows the entry, manipulation and storage of data in a database format. database management systems offer a possibility of reduced data redundancy if the database is well-planned and structured. relational databases created with database management software are the most flexible databases and are very easy to modify.
54
what is the function of a DBMS
he functions of a database system include:
- the facility for entry of data into fields
- the ability to sort records on one or more fields
- the storage of file(s) according to the software managing the data
- the retrieval of records which satisfy certain criteria through the use of query language
A DBMS contains backup and recovery capabilities to guard against loss of data. a backup is a copy of the data that is used to rebuild the system. A DBMS creates a backup at a specified time, usually at night when the database is not being accessed. Backups are usually stored off-site or in a fireproof safe
55
what are the 3 most common methods of access to files in a database
- sequential access
- indexed sequential access
- direct (or random) access
56
what is sequential access
sequential access: where each record in a file must be access in a series from first through to last. the records are arranged in ascending or descending order according to a key field. sequential file access means that each and every record in the file must be read before the desired record can be accessed. sequential file access is advantageous when every record has to be displayed or updated and, in addition, such files are easy to design. the main disadvantage of sequential file access is that by its very nature it is slow to access records. sequential storage is usually done on magnetic tape although it may be on disk, CD or DVD
57
what is indexed sequential access
indexed sequential file access - improves on the sequential file access method by allowing serial access starting at various locations marked with pointers. records are still stored in a file in a sequence according to a key field. the storage system establishes one or more indexes to associate the key field with the storage location of the record on file. this makes the system faster then the sequential file access, as the indexes are read first to establish the location of the record and then the records in that group are read through sequentially until the desired record is found. fairly complex software is needed for such a means of file access, but it is faster than the sequential file processing method
58
what is direct (or random) access
direct (or random) access - of files still uses the key field to store the records but also uses the key field to generate the address of the location of that record in the file. this allows access to any file or record in any order. where only some records need to be accessed, direct (or random) file access is the ideal method. direct access is certainly time saving, as not all records have to be accessed. the disadvantage of direct access is that ensuring security of data is more difficult
59
what is online and offline storage
Off-line storage refers to data stored such that it cannot be accessed until the storage media is mounted into a drive. Common examples of off-line storage include magnetic tape, optical media such as CDs and DVDs and other portable drives such as thumb or USB storage devices. In terms of large information systems off-line storage is used to maintain backup copies of the on-line data.
On-line storage is available immediately to connected computers. It includes hard disks within a single computer and also storage devices accessed via a network or even over the Internet. On-line storage is usually in the form of hard disk drives, however tape libraries, CD and DVD juke boxes can be used to provide on-line access to tape and optical media. Conversely, systems also exist where hard disk drives are used for off-line backup.
On-line storage over the Internet is becoming common. In this case a third party organisation provides secure, yet flexible, backup and restore services. Many of these services allow backup copies of individual files to be opened and saved on-line across the globe.
60
what is a centralised database
centralised - has all its data residing in one place that is accessible from a number of remote locations
- Database that is stored at one central location but is available for use by all computers on the network
- Single copy of the database makes data management and security easier
- No synchronisation required
- Entire network relies on the single computer that stores the database
- All reliant on the single computer, if it fails then the entire network fails
- is easier to manage, update and backup
61
what is a distributed database
distributed
- Geographically dispersed among different computers at different sites, but acts as a single database
- Reduces transmission costs
- All files are available to authorised users via a network
- More prone to security issues
- Synchronisation is required in a distributed database to make sure the database is current or else issues of data integrity may arise
62
what are some examples of storage media
- hard discs
- CD-ROMs
- cartridge
- tape
63
what is a hard disc
- A double sided disk/platter made of metal or glass and covered with a magnetic material in a vacuum sealed casing to protect disk (pretty mirror disk with needle taken apart from class)
- Data is arranged into tracks and sectors within concentric circles
- Direct access to retrieve data and is online storage and can be used for offline backup
- Fast, reliable, high capacity (measured GB)
64
what is a CD-ROM
- Optical disks use laser technology to read and write data
- Stronger lasers used to store data and weaker lasers used to retrieve it
- Inexpensive, reliable and portable
- Can store reasonable amounts of storage, usually music/picture
65
what is cartridge and tape
cartridge
- Magnetic tape encased in a cartridge
- Comes in different sizes to match tape
tape
- Long, thin strip of plastic coated with a thin layer of magnetic material
- Stores large quantities of data inexpensively
- Often used as a backup medium and has sequential access
66
what is encryption and decryption
the most effective way of securing data is through encryption. encryption is the process of translating data from its original form into a code. a password or secret key is then needed for file decryption (decoding) which is the reverse of encryption. data in its unencrypted state is referred to as plain text. once it has been encrypted, the data is called cipher text
67
what is symmetric and asymmetric encryption
- asymmetric encryption requires a key for encryption and a key for decryption. it involved a public key that is used to encrypt data and is widely available and a private key that decrypts the message and is kept secret
- symmetric encryption requires the same key for both encryption and decryption
68
what are some techniques for securing data
- backup and recovery - the copying of files to a separate storage device in case the first device fails or data is lost. the backup should be stored in a different location or off-site. there are two types of backups: full backups or partial backups. a full backup includes all files whereas a partial backup is only of the data created or changed
- physical security measures - eg locks
- usernames and passwords - used to assign levels of access to the database to ensure that more sensitive data is not available to everyone
- restricting access using DBMS views - in a form view, certain data can be hidden (not displayed) so that sensitive data or non-critical data is not displayed to all users
- record locks in DBMS - locking individual records prevents two users from making changes to a record at the same time. record locks can allow the system to check if there have been changes made and then store the more current record
69
what is sorting ? what are the three methods of sorting?
- Sorting is the arranging of items of data in a particular order. There are three methods of sorting:
- ascending order where data is arranged from the smallest to the largest (A to Z or 0 to 9)
- descending order where data is arranged from largest to smallest (Z to Z or 9 to 0)
- multiple-field sorting where more than one criteria is used for the sort. For example, in a school database, students may be sorted on Surname first and then on FirstName.
When a database is sorted, records are actually moved to a different position in the database display (it does not change the actual order of the stored records). Different fields are part of a record and cannot be separated from it.
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what is reporting
reporting - while a selection only produces a soft copy of records that satisfies a set of rules, reporting permits the production of a hard copy. for example, in a report which includes the names and addresses, a set of mailing labels can be printed
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what are calculated fields
calculated fields - a calculated field is determined using numerical data from other fields. the field will contain a formula using data from other fields. for example, a formula can be entered into a field to calculate the average of students marks which are stored in other fields
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what is searching
Data needs to be quickly and efficiently retrieved from a database. Searching is the process of examining the database to retrieve data. An effective search in a small database may involve reading through a table or using the Find or Search command. However, in a large database, the most efficient way of searching is to construct a query. A query is a search of a database for records that meet a certain condition. It is a question you ask of the database.
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what is a Query By Example (QBE)
- Query by example (QBE) is a visual technique for specifying a database query
- QBE usually provides a form that allows users to indicate the data they are searching for by entering or selecting data within appropriate fields. Criteria for selection may be single items or several, linked by relational or logical operators.
- Queries by example can be used by participants with no formal programming training to get the information they need from the database. (advantage)
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what are relational operators used for and what are some examples
relational operators are a part of query language that allows the values to be compared. relational operators may be used individually or in combinations in order to extract the required information. eg < = >
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what are wildcard operators and explain how they work
- wildcard character represent one or more unknown characters.
- Some common wildcard characters are the asterisk (*), which substitutes for any number of characters, and the question
mark (?), which substitutes for one character. The query 'LastName = Ma*' would find such last names as Mat, May, Madrid and Martinelli. However, the query 'LastName = Ma?' would only find such last names as Mat and May.
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what are logical operators and what are some examples
- Logical operators (AND, OR, NOT) are used to combine queries so that a search is carried out on one or more fields. It is important to understand the difference between the AND and OR operators:
- the AND operator requires both the first and the second query to be true. It retrieves records that satisfy both queries.
- the OR operator requires either the first or the second query to be true. It retrieves records that satisfy either of the queries. **question: is it A OR B but not A AND B or A OR B or A AND B*
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what is Structured Query Language (SQL)
Structured Query Language (SQL) is a query language used to access and manipulate data in a relational database.
- select: The data to be displayed . E.g : SELECT Students.FirstName, Students.LastName
- from: the source of the data. E.g : FROM Students, Scores
- where: The query/search criteria. E.g: WHERE LastName = “Mullins”. If multiple tables, Students. LastName=”Chen” AND Scores.Mark > 1000
- order by: Order in which the results are to be displayed. E.g: ORDER BY LastName DESC
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what is free text searching
- A program that will look for specific characters in an open document
- E.g: Find command in a web browser or word processor. (ctrl f)
- Only searches for the specific text characters in the page currently open
- Limited to the displayable text in open web-page.
- Will not search through the metadata for any hidden information such as the name of the page author, creation date, etc
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what are search engines
Search engines enable web users to locate web pages about specified topics. The user enters a search criteria (which may be in the form of natural language) and the search engine returns a list of matches. eg google, yahoo.
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what are the two techniques used to locate web pages
Traditionally there are two distinct techniques used to locate web pages; the first is used by web directories and the second is used by search engines.
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how do web directories work
Web directories are created by humans based on submissions from users. Commonly the creator of a new website submits details of their site to the web directory, the details are checked by an employee who then adds the site to the appropriate directory.
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how do search engines work
Search engines use automated software tools called search robots. These robots crawl the web and automatically locate and index individual web pages. Some search engines examine keywords specified within HTML metatags, whilst most determine their own keywords as they examine the content on each page.
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what is indexing
- Index = table that contains information about the location of data
- A search engine’s index is built by regularly scanning the Web for new sites
- Indexing software collects information, such as titles and keywords, from the Web sites, then indexes these words in a database
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what is a search robot
- Scanning is often completed by programs called spiders, crawlers or robot
- Gathers information for search engine indexes
- Each web page is downloaded, examined for hyperlinks and passed onto the indexer
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what is metadata in search engines
- A list of a web page’s keywords embedded in the header section of its HTML code.
- It is usually defined by the tag so that search robots can easily identify it, without needing to look through entire page.
- Search engines robots may look at metadata to find descriptions and keywords of each webpage they index
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how is reported data found in hypermedia systems
- Involves search engines using a page-rating or relevance calculation method to decide the order in which the URLs are displayed on the search results page
- Can determine the popularity of a web page by the number of links that connect to them
- If a keyword appears in the title of the page, engine will consider it relevant and place it at the top of the search results
- Too many keywords in a page may represent spam
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how do you get the storage requirement for a record in a data dictionary
the data dictionary should define the size of each field. adding these values for each field in the record will give the storage requirement for one record (in bytes B)
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how do you get the storage requirement for each file (table)
the data dictionary should define the size of each field. adding these values for each field in the record will give the storage requirement for one record (in bytes B)
multiplying by the number of records will give the storage requirement for each file (table)
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how do you convert between bits, bytes, kilobytes, megabytes, gigabytes, or even terabytes
8 bits (b) = 1 byte (B) -> binary
1024 B = 1 kilobyte (KB)
similar for rest (divide by 1024) in this order:
bytes, kilobyte, megabyte, gigabyte, terabyte
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what is a report
A report is formatted and organised presentation of data and are designed to be an easy way to present printed output from a database. DBMS contains report generators allowing users to have control over what data is displayed in different formats
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what will a typical report produced by a DBMS include
- a report header (company’s logo, report title and date)
- a page header (title, column headings)
- details (the specified fields from the selected records from the database)
- a page footer (date, page number)
- a report footer (report totals)
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when designing a report or form, what are some good design principles that must be thought about
- consistency of design
- the appropriate use of white space
- grouping of information
- a document heading to identify the purpose of the report
- headers and footers containing the date and page numbers
- columns that have meaningful names for headings
- a good balance of text on page
- consistent formatting of text throughout the report
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what are some issues related to information systems and databases
- acknowledgement of data sources
- the Freedom of Information Act
- privacy principles
- quality of data
- accuracy of data and the reliability of data sources
- security
- access to data, ownership and control of data
- data matching to cross link data across multiple databases
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what is the freedom of information act
access to data, ownership and control of data
- databases store private information on individuals as well as confidential information on organisations. access to this data should be controlled by the security methods already outlined.
- the commonwealth freedom of information act 1982 and the new south wales freedom of information act 1989 both allow individuals to find out what data is being kept on them in government and non-government organisations
- states that an individual has the right to access information related to the individual and does not invade the privacy of another
- an individual can request amendments to records that are inaccurate and can appeal against decisions that will not allow them to access their information or to have it changed if it is incorrect.
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what is data integrity
Data integrity refers to the accuracy and reliability of data and measures the quality of data. data integrity can be maintained by ensuring that the database is able to resist
- user mistakes
- system malfunctions
- deliberate or accidental alteration
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what are some aspects of data quality
- Collected data needs to be verified(making sure it is correct)
- Manually compare collected data to the source data
- Contacting the user to confirm accuracy
- Repeating to the operator
- Double reading what they’ve entered
- Accuracy (well written, acknowledgements)
- Authority (who are the people responsible for information)
- Objectives (free from advertisements - commercials, trying to sway my opinion)
- Currency (up to date)
- Coverage (is the information complete, is it detailed
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what is data verification
- data verification is a check to ensure that the data collected and stored always matches the source of the data.
- when collecting data over the phone, it is a ready back to you by the operator
- when entering data online, a report displays the entered data for the user to check before submitting
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what is data validation
- data validation is a means of checking its accuracy and appropriateness in the data entry stage using software. this can be performed in a number of ways:
- checking that the data is in the acceptable range
- checking that the data is in the required format
- checking the number of character in the field/record
- implementing cross-checking facilities
- selecting data from a list
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what is data bias and how might it occur
- data bias may occur in the way in which the data is collected and manipulated, as well as in the way it is gathered.
- devices that can capture data in a machine-readable form will be less likely to input biased data
- rejection and editing of some of the collected data or collection of data from non-representative sources can also cause the data to be biased and therefore unreliable.
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what are some examples of security measures in a system
- restrictions on the level of access employees have to files and fields in the database. unauthorised users are called hackers
- passwords designed to restrict initial entry into the database to authorised users only
- closed-circuit television monitoring in computer areas containing sensitive and important data to observe users
- data encryption to scramble displayed sensitive or private material should unauthorised persons gain view of a monitor or if a computer is left unattended
- backups of data on a regular basis in case loss or corruption of data should occur
- a firewall can be used on the internet or any network to ensure that all incoming data is authorised. it checks the password of anyone entering the network
- data matching to cross-link data. data is brought together from different sources and compared. this can be used to identify and prevent fraud. this is often done with personal information
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what is access to data
- Access to data is the extent to which data is available to people
- Access to private data reveals individual preferences, weaknesses and habits, which are used by companies to their advantage eg. target advertising using loyalty card data
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what is data matching
data security - data matching to cross-link data. data is brought together from different sources and compared. this can be used to identify and prevent fraud. this is often done with personal information
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what is data warehousing
- A place where non-active or old data is collected and stored
- Supports management decision making and designed for reporting and analysis
- Data warehouses are extremely large storage areas of raw data
- High costs due to lots of storage needed and maintenance
- Used for business analysis, data and market analytics, and business reporting
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what is data mining
- Process of discovering non-obvious patterns within large collections of data
- Analysis of large data stores to discover hidden patterns/trends that weren’t obvious or predicted by conventional querying of a database
- E.g: Data mining software may detect a pattern indicating that men tend to buy luxury food items early in the week if they are also purchasing nappies
- Companies can take this knowledge and exploit it to target customers
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what is Online Analytical Processing (OLAP)
- Online Analytical Processing
- A technique for providing business decision makers with statistical evidence, largely based on past trends, upon which they can make intelligent decisions
- Used with data mining
- Aims to provide information visually, online, as needed as a quickly as possible
- OLAP tools optimise the organisation of large data stores so that decision makers can simply and quickly get answers to assist them to make decisions
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what is Online Transaction Processing (OLTP)
- Online Transaction Processing
- Databases that allow transactions to be processed immediately by remote users
- Completing an online purchase over the Internet is a common example of a transaction performed by an OLTP system
- Such financial transactions must occur in real time as funds are moved from one bank account to another and then the purchase is confirmed
- E.g: ATM, e-commerce, airlines
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what is DBaaS (Database as a Service)
- Database as a service (DBaaS) is a cloud platform that provide users with the infrastructure that databases require, along with security and resource management
- DBaaS have many advantages, providing services that help transfer and transform existing database systems to the cloud, providing businesses with flexible storage options, several backup and recovery options, extensive security and access from various locations over the web.
- DBaaS does have downsides, including size limitations and outsourcing security, and performance that is dependent on web traffic, server speed and the quality of infrastructure that the cloud service provides
