Year 12 IPT Summaries

Topic 2: Information Systems and Databases

Information systems

the characteristics of an information system, namely:– the organisation of data into

information: Data must be organised before it can be stored and analysed by the information system. Organising may require sorting, summarising or classifying. Data in an information system is organised into data structures using such organisational methods as data dictionaries.

– the analysing of information to give knowledge: knowledge from accessing information is the purpose of an information system. The information must be analysed in order for this to be achieved. Information systems provide a range of tools for the analysis of data, such as tables, queries and reports. People make decisions based on the information they receive from an information system.

the different types of and purposes for information systems, including systems used to:– process transactions. Transaction processing systems collect, store, modify and retrieve the

daily transactions of an organisation. Some examples of the application of TPSs are buying goods at a point-of-sale (POS) terminal, processing credit card payments and tracking receipts of materials from suppliers. Organisations rely heavily on their TPS. There aretwo types of transaction processing: batch processing and real-time processing.

– provide users with information about an organisation. These provide information about the performance of the organisation to the managers. This involves the production of reports on sales, inventory, payroll, orders and payroll. This is used to make decisions and motivate employees

– help decision-making. Decision support systems (DSSs) assist people to make decisions by providing information, models and analysis tools. A DSS can be used on a daily basis or when an organisation has to react to something unexpected or make changes. One example of a DSS is a system that analyses the stock market and helps the user make decisions about buying and selling shares. A DSS creates a mathematical model of the variables affecting the decision, using statistical tools, databases, spreadsheets and graphics. The model allows a manager to ask what-if questions by changing one or more of the variables and seeing the projected results. The DSS depends on the accuracy of the mathematical model and the ability of the manager to formulate appropriate questions. Expert systems are a type of DSS.

– manage information used within an organisation. These provide an effective way to complete tasks in the organisation. A variety of appropriate software tools are available for the editing and production of high quality documents and to provide both internal and external communication.

Major types of information systems:Type Purpose Resources & Processes UsedTransaction processing system (TPS)

Processes transatcions Collection & storageBackup of dataBatch & real-time processing

Decision support system (DSS)

Provides information to help with analysis and make decisions

Risk anaylsisModelling toolsSimulationsCost-benefit analysis

Management information system (MIS)

Provides information to help with routine daily tasks of managers

ReportsBudget summariesProduction schedulesStock inverntories

Office automation system (OAS)

Uses technology to operate office administration

NetworksHardware: fax, computer, printersSoftware: word processors and other applicationsCommunications such as video conferencing and email

Database information systems school databases holding information on teachers, subjects, classrooms and studentsEnvironment: school community (students, staff, parents), educational services offered by the school, the flow of information between the school and authorities such as the NSW BOS and NSW Department of Education and Training, the hardware and software.Purpose: to maintain the efficient operation of the school, its personnel, finances, resources and administrative tasks. It also provides information on student enrolments, subject selection and assessments and must meet all legal requirements for monitoring student attendance. Data/information: equipment register, finance and purchase orders, GST records, library resources and loans, staff information, student attendance information, student marks and grades, student personal and academic information, timetables and room allocations.Participants: School office staff, library staff, teachers, students.Information processes: data collection (enrolment forms, marking class rolls, fee payment, recording marks, library loans and returns); data is organised and stored in a variety of databases that deal with student and staff information, resources and finances; data is analysed and processed to create class lists, student reports, financial reports, purchase orders, receipts and overdue book lists; data is transmitted and/or received from educational authorities such as BOS and DET. Input data and information are displayed on VDUs (visual display units) and printouts.Information technology: keyboard, monitor, barcode reader, printer/s, networked computers/ terminals, software such as OASIS office network administration system, Motorised Markbook, spreadsheet application software, personal database systems and other software applications.

the Roads and Traffic Authority holding information on automobiles and holders of drivers licences

Environment: drivers, driving instructors, driver examiners, vehicle owners, vehicle inspectors, RTA services such as registration and licensing, the flow of information between the RTA and the NSW Department of Transport, the police, the courts, the hardware and software.Purpose: To manage the registration of all drivers and motor vehicles in NSW. This includes sending out vehicle registration payment requests. Also, it provides statistical information on drivers and vehicles to the government and registration information to other authorities like the police. Data/information: driver personal details, driver payment details, driver licence number, licence type and classification, driving history (inc. points remaining), vehicle identification number, make and model, 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 the RTA offices, motor registries and vehicles inspection stations. Also, The Police Department Traffic Branch as it monitors driving records and vehicle registrations. Information processes: Data is collected from registration application forms, licence applications, renewals, vehicle inspection and driving test results. The data is organised and stored in a number of different databases that deal with drivers, vehicle information and finances. Processing occurs when vehicle registration and licence renewal forms are sent out. Data analysis produces statistics on registered vehicles and licensed drivers. Data on vehicles and drivers is transmitted to the Police and other authorities when required. Both input data and information are displayed on VDUs and printouts. Information technology: Hardware: keyboards, monitors, EFTPOS machines for credit/debit card payments, barcode scanners for registration notice payments, and networking between the computers in the office/building and links to state WAN. Software: DRIVES the integrated driver licensing and vehicle registration database software system used by the RTA (DBMS).

video stores holding information on borrowers and videosEnvironment: customers and staff, suppliers, entertainment and other services supplied by the store, the flow of information between the store and its head office, the hardware and software.Purpose: to keep accurate records of the stock, both the rentals and sales, particularly the rental stock out on loan. It also serves as a transaction processing system to collect data for further analysis by store management.Data/information: customer details (including current loans and overdue items), video rental title records (including items in stock and on loan), saleable item records (DVDs, snack foods), rental and/or sales figures for each item, GST records.Participants: Staff who check out DVDs and other products, process returns, authorise orders for new stock. Also, head office managers who use data provided by the system

Information processes: Data is collected from membership applications, sale items and rental DVDs passed over the scanner, and new products that arrive at the store. The data is organised and stored in product and customer databases. Processing occurs when products are sold, rented, returned or arrive as new products. In the case of a DVD rental or return, both the customer’s record and DVD item record in the same databases are updated. Data analysis produces statistics on DVD rentals, sales, delinquency rates (non-return of DVDs), and store income. Some of this data would also be transmitted to head office (if applicable). Both input data and information are displayed on VDUs and printouts. Information technology: keyboard (for data entry), monitor, barcode scanners (main input device as all products for rent/sale and membership cards are barcoded), (printer?), DBMS, sales software, network communications software.

Organisation non-computer methods of organising including:

– telephone books. Subscribers surnames are sorted alphabetically. Searching for the person’s name retrieves their phone number

– Dictionary. Words are sorted alphabetically.– card based applications such as recipe cards that are sorted into categories such as salads,

chicken, desserts– Photograph album. Photos are organised chronologically.

computer based methods of organising, including:– flat-file systems: organises data into a single table and is suitable for many small

applications. Flat file databases organise data using data structures called files, records, fields, and characters. Only allows you to use and manage one database at a time.

– database management systems: is a software package that allows users to access a database so they can enter, maintain and view the data. The data is independent from the DBMS. In a DBMS, data is organised into tables, viewed in forms, retrieved using queries and displayed in reports. A DBMS manipulates the data in many different ways, such as sorting and searching. A DBMS allows you to simultaneously manage and use several separate databases. It allows you to build relationships between the data in different databases. A DBMS is the software package that makes the flat file and relational databases.

– Hypermedia: A combination of media whose locations are linked to provide an easy way to navigate between the documents. It is used a lot on the internet. Hypermedia-based data organising systems are not as simple to create as flat file databases and generally have limited data processing capabilities. Hypertext is a system that 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.

– Relational database: organises data using a series of related tables. A DBMS is relational. Every record has a unique key field or unique combination of fields forming a compound or composite key. There is reduced data redundancy and shared data. All data is stored in tables. There are consistent reports as the data is in a central place and thus the correct updated data appears on all the reports extracted from the database. There is also centralised security (greater control over levels of access as all in one place). The schema is an overall view which shows how the tables are linked. Data can be viewed for different purposes using a variety of formates including: table view (all records displayed in a table format, images not shown), form view (each record displayed separately; used for data input and displaying images), and report view (output of data for printing; report can have headers, footers, a title and logos so that hard copies can be made; can include information from a query or table and is used to present data from one or more records). Relationships are built between tables to provide a flexible way of manipulating and combining data.

Figure 1 Schematic diagram of a relational database

Identify situations where one type of database is more appropriate than anotherIn general, if you need instant access to data in any situation (including in a bus or in a taxi) then manual methods will often be more efficient. However, manual methods are generally limited to simpler tasks, involving smaller quantities of data. If you need to perform complex processing tasks, have larger quantities of data or the data is quickly changing, then computer-based methods will be more efficient. However, they are usually less convenient or portable. Choosing between the three computer-based methods will be a matter of deciding if:

the data has to be widely distributed but little or no processing is 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).

the advantages and disadvantages of computer based and non-computer based organisation methods

Organisational Method

Advantages Disadvantages

Manual -Does not require a computer, a power supply or batteries-Highly portable, weighs very little, fits inside a bag (mostly)-No special skills/training needed to use them

-Very inflexible layout-Access is usually by one method only-Usually only one person can access the data at any one time

Computer-based

-Considerably faster-Data does not have to be in a set order-Data management is much easier-Data can be easily exchanged between applications and over networks

-Data can only be accessed if you have a computer-less portable-Training is usually required-Exchange of data with other computers creates problems of security and confidentiality

the logical organisation of flat-file databases, including:– files: a block of data and is divided into a set of related records.

– records: a collection of facts about one specific entry in a database and is divided into one or more related fields

– fields, key fields: A field is a specific category of data in a database and is made up of characters. A key field is a field that uniquely identifies a specific record. Every record must use the same field as its key field and no two key fields can contain identical data.

– There are four types of keys: single (a field in which each item of data is unique), composite (made by joining two or more fields together. It is used when no data item in any field can be guaranteed to be unique.), primary (single key or compound key that must have a value) and secondary (a field that contains useful items of data often used in searches. They are not always unique).

– characters: is the smallest unit of data that people can use. Characters include letters, numbers, and special symbols.

Figure 2 the logical organisation of flat-file databases

the logical organisation of relational databases, including: schemas (An organised plan of the entire database showing how and where the data is

found, descriptions of the data and the data’s logical relationships.) as consisting of:- entities: a specific ‘thing’ about which an information system collects and processes

data. In a database of students, each student is an entity.- attributes: a defined property of an entity. Attributes are the columns in a relationship

table shown in list view. It is a field copied from a parent database.- relationships: the way in which entities are

related to each other. The key field is used to link entities. one to one: each record in the first entity is

related to exactly one record in the second entity. Eg. One primary school teacher is assigned to one class

one to many: each record in the first entity relates to many records in the second entity. Eg. A high school teacher is assigned to many classes.

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. Eg. Each student studies many subjects and many students study each subject.

– tables as the implementation of entities consisting of:

Entity=Table E Two

Attribute=Field A Fish

Tuple=Record T Regularly

Information about an entity is displayed in a table

- attributes. A column 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.

– linking tables using primary and foreign keys. Primary key: a field that stores data that uniquely identifies the record. Usually an ID number. Foreign key: an attribute which is the primary key for another table.

Director Table

Director Number (PK)

First NameLast Name

Figure 3 a schema showing the linking of tables using primary keys (PK) and foreign keys (FK) in a one to many relationship.

– user views for different purposes. Data can be viewed for different purposes using a variety of formates including: table view (all records displayed in a table format, images not shown), form view (each record displayed separately; used for data input and displaying images), and report view (output of data for printing; report can have headers, footers, a title and logos so that hard copies can be made; can include information from a query or table and is used to present data from one or more records).

data modelling tools for organising databases, including:– data dictionaries to describe the characteristics of data

including:- field name: the name of the field as it appears in the

database. Should be carefully selected to avoid confusion.

- data type. Includes text/alphanumeric, numeric, Boolean or logical, date, time, calculation.

- data format: any special formatting applied to the field. Shows how the data is to be displayed. Eg. Number of decimal places, DD/MM/YYYY.

- field size: the number of characters allowed for a given field. The field size can be used to determine the storage space required. If field sizes are kept to a reasonable size, the database will work more efficiently.

- description: a simple description of field contents. It specifies the content of the field.- example: a typical field entry. It illustrates possible valid content.

Field name Data type

Data Format Field Size

Description Example

User ID Text NNNNNNNN 8 Unique eight digit number represented as text

0001539

First Name Text 25 First name of employee BillSurname Text 25 Surname of employee SmithDOB Date DD/MM/YYYY 10 Date of birth as a short

date format15/07/1982

Hourly Pay Rate

Currency #####.## 8 Rate of pay expressed in dollars per hour

34.50

1

∞

A data dictionary contains metadata, or information about data.

Film TableFilm Number (PK)Film TitleRatingDirector Number (FK)

Hypermedia is is a combination of media whose locations are linked electronically to provide an easy way to navigate between the information. Hypertext is a system that allows documents to be cross-linked in such a way that the user can move from one document to another by clicking on a link.

Node: A device in a network.

Height Real #.## 3 Height in metres, with two decimal places

1.58

Fees Paid Boolean 1 Y or N for Yes or No YFigure 4 an example of a data dictionary

– schematic diagrams that show the relationships between entities. 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 in excluded or included from an entity. normalising data to reduce data redundancy. Normalisation is the process of organising

data into tables so that the results of using the database are unambiguous and as intended. It is the process of normalising the design of a database to exclude redundant data. It is a refinement process that aims to reduce data redundancy by removing repeated fields and grouping them as a new record. Normalisation results in a database that is more efficient but more complex because data is separated into more tables. It involves dividing the database into two or more tables and defining relationships between tables. The objective is to isolate data so that additions, deletions and modifications of a field can be made in just one table and then spread through the entire database via the defined relationships. Normalising results in improved performance of the database, especially in loading speed. There are three main normal forms, each with increasing levels of normalisation:

First Normal Form (1NF). Each filed in a table contains different information. Eg separate name into first and last namesSecond Normal Form (2NF). No field values can be derived (got) from another field. Eg if have DOB don’t need year of birth.Third Normal Form (3NF). Each non-keyfield should be a direct description of the primary key field. You must place any fields that do not relate directly to the primary key into another table. This will avoid the repetition of data.

the logical organisation of hypermedia, including:– nodes and links. A link, or hyperlink, is

indicated by a highlighted item (usually an underlined word or a graphic) that allows the electronic connection. The author of the hypertext must specify the location of the information accessed by each link. If another computer is the destination of the link, that computer is called a node.

– uniform resource locators: is the address of the file or resource on the web. The main parts of the URL are the:

protocol—the transfer method used to access a particular resource on the Web. It identifies the format and method of transmission to be used. In most cases the protocol will be ‘http://’ (hypertext transfer protocol). domain name—address of the specific computer where the resource is located, such as www.hi.com.au’. It is the name for the website on the Internet. The domain name can be replaced by the IP address.file path—the full path to the file to be retrieved. It may be a simple filename, or it may be a directory path, such as ‘atlas/about.htm’. The domain name and the file path are separated by a forward slash (/).

– metadata such as HTML tags. Hypertext markup language is a set of special instructions (called tags) that indicate how parts of a document on the Web will be displayed and navigated. A HTML tag is an instruction in HTML.

Anchor Filename Pathname for different location Hypertext referenceHypertext link to document

<AHREF=http://www.smh.com.au/crossword.html/>crossword</A>Figure 5 an example of HTML tags

tools for organising hypermedia, including:– storyboards to represent data organised using hyperlinks. A storyboard is a series of

frames, each representing a different action or screen image. It shows the navigation between frames. There are four storyboard layouts:

linear—a simple sequential path that is set up quicklyhierarchical—a sequential path in a top-down design; the user starts at the beginning and moves down through the multimedia productnon-linear—no structure; the user moves between different layouts in any directioncombination—a blending of the above layouts.

Figure 5 Storyboard layouts

– software that allows text, graphics and sounds to be hyperlinked. HTML is the primary tool used to link on the internet. Software that links data includes:

o Hypertext Markup Language (HTML) is a set of special instructions (called tags) that indicate how parts of a document will be displayed and navigated. HTML files are text files that contain HTML tags. HTML editor is a software program that specialises in writing HTML code. HTML tags are the instructions or metadata. A tag is made up of a left (<) and a right angle bracket (>) and a tag name. Eg. <a href=“URL”> creates a hyperlink to the URL. Links are achieved by using a hypertext-related tag.

o Web page creation software such as FrontPage and Dreamweaver. These allow for the creation of web pages without the having to type the HTML tags. The required tags are automatically inserted by the software and the generated web pages can be viewed in the HTML form or as seen on the web browser. These are WYSISYG (what you see is what you get) programs.

A DBMS is a software package that allows users to access a database so they can enter, maintain and view the data.

A database contains the data, and the DBMS provides access to this data.

Storage and retrieval database management systems (DBMS) including:

– the role of a DBMS in handling access to a database. The functions of a DBMS 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 and the retrieval of records which satisfy certain criteria through the use of query language. It also includes back-up and recovery capabilities to guard against loss of data.

– the independence of data from the DBMS. Data independence is the separation of data and its management from the software applications that process the data. The degree of data independence should be high to decrease the costs associates with ongoing maintenance of the database. There are two aspects of it:

o the physical organisation of the data is achieved when the operating system determines the way in which data is physically organised on the storage medium. If the user has to determine this, there is no physical independence.

o the logical organisation of the data is how the program defines the data. The user’s interpretation or view of the data is determined by the DBMS.

direct and sequential access of data. Direct access occurs when data is accessed without accessing previous data items. Data is stored in a particular storage location based on a mathematical procedure or algorithm. Direct access often involves the use of an index and is then called indexed access. An index is a table that contains information about the location of the data. Eg. Optical disks, memory cards, USBs. Sequential access occurs when data is accessed in a sequence. It means that the data must be stored and retrieved in a linear sequence. Sequential access processes data in the order it was stored. It does not require the exact location of the data item. Also, it is much slower than direct access and impractical when immediate processing is required. Eg. Magnetic tape.

on-line and off-line storage. On-line storage uses a peripheral device that is under the user’s direct control, such as a hard disk on a personal computer. Online storage over the internet is becoming common. Off-line storage uses a peripheral device that is not under the user’s direct control, such as a centralised database. It refers to data stored such that it cannot be accessed until the storage media is mounted into a drive. It is often sued to maintain backup copied of the on-line data.

centralised and distributed databases. A centralised database is a single database under the control of a single DBMS. All users and client applications connect directly to the DBMS. It works well on a single site; however performance problems begin to emerge as user numbers increase. A distributed database is a database located at more than one site. It acts as a single collection of data but is geographically dispersed. It is a set of connected databases stored on multiple computers that appears to users as a single database. Distributed databases reduce the data transmission costs that would occur if all users at all sites had to access one centralised database. However, a distributed database makes it more difficult to obtain a complete view of the database. A two-phase commit is part of the DBMS used to maintain consistency across a distributed database. It checks whether both parts of the database are ready for the transmission and then performs the transmission. There are many types of distributed database system including:

o Fragmentation: different parts of the database are stored at different location. Individual data items are physically stored once only at a single location.

o Downloading: each server downloads copies of data as it is required from remoter databases and stored the data within its local database. This is suited to data that rarely changes yet fast data access times are required.

o Replication: the aim is for all local databases to hold copies of all the data all the time- in reality each local database holds most of the data most of the time. Each replicant is synchronised with the master at regular intervals. This suits systems where the same records are rarely altered or added at similar times but at different sites.

storage media including:–Magnetic storage: currently the most popular method for maintaining large quantities of

data. The zeroes and ones (that make up digital data) are spaced along the surface of the magnetic medium so they pass under the read/write head at equal time intervals. Eg hard disks.

– hard discs store data magnetically on precision aluminium or glass platters. The platters have a layer of hard magnetic material into which the magnetic data is stored. Each platter is double sided. It allows for direct access at high speed for both storing and retrieving processes.

–RAID (redundant array of independent disks): utilises multiple hard dick drives together with a RAID controller. The RAID controller manages the data flowing between the hard disks and the attached computer. The attached computer sees the RAID device as a normal hard drive. A RAID controller can be dedicated hardware or a software program. RAID is based on two basic processes: stripping and mirroring. Stripping splits the data into chunks and stored chunks equally across a number of hard disks. Mirroring involves writing the same data to more than one hard disk at the same time.

–Optical storage: the processes are based on reflection of light: either the light reflects well or poorly back to the drive’s sensor. It is the transition from good reflection to poor reflection (or vice versa) that is used to represent a binary one; when refection is constant, a zero is represented.

– CD-ROMs (compact disk read only memory) contain a single spiral track that commences at the inner portion of the disk and spirals outward. It is able to store up to 680Mb. DVDs contain similar but much more densely packed tracks, each track can store up to 4.7Gb. Additionally, DVDs can be double sided and can also be dual layered. Thus, a double sided, dual layer DVD would have 4 spiral tracks and up to 17GB may be stored on it.

– cartridge and tape are inexpensive backup mediums. The ability to backup the entire contents of virtually any hard disk using just one tape far outweighs the disadvantages of sequential access. encryption and decryption. Encryption is the process of encoding data. Decryption is the process

of changing it back (decoding). It is the most effective of securing data during transmission. Data is encoded, transmitted and then converted back to its original form. One problem with encryption is to find a method that is difficult to decode but practical to use. There are two main types of encryption:

o Asymmetric encryption requires a key for encryption and a key for decryption. It involves a public key that is widely available (to encrypt) and a private key that is kept secret (to decrypt).

o Symmetric encryption requires the same key for both encryption and decryption. A common symmetric encryption system is the Data Encryption Standard (DES).

backup and security procedures. A backup is another copy of the data that can be used to rebuild the system. If a computer fails or the storage media/database is damaged, the costs of interrupted operations and replacing any lost data can be enormous. A DBMS contains backup and recovery capabilities to guard against data loss. Backups are usually stored off-site and may be in fireproof safe. There are two types of backups:

o A full backup includes all fileso A partial backup includes only those files that have been created or altered.

Data can be stolen, destroyed or maliciously modified. Data security involves a series of safeguards to protect data. This includes use of usernames and passwords, biometric devices, personal objects, and firewalls. Data can also be encrypted. Restricting access using DBMS views and record locks in DBMS are also security measures. Additionally, there are also physical security

measures where the physical location where servers are stored is locked and access is gained using keys, pass cards or pin numbers.

calculate the storage requirements for a given number of records (given a data dictionary for a database). File size= sum of field sizes x no. of records = Kb

1024 tools for database storage and retrieval, including:

–extracting relevant information through searching and sorting a database. Sorting is the process of arranging data in a particular order. Sorts are performed in either ascending or descending order. It can be done on more than one field (attribute) so that records are arranged in the most useful order. Note: sorting does not change the order of stored records, rather the order in which the records are displayed. Searching is the process of examining the database to retrieve data.

–selecting data from a relational database using Query by Example (QBE) and Structured Query Languages (SQL) commands, including:

-SELECT: The data to be displayed-FROM: The source of the data-WHERE: The query-ORDER BY: The order in which the results are to be displayed

Structured query language (SQL) is a programming language that uses a set of common commands to extract information from databases.

Syntax (keyword)

Source Description Example

SELECT Field/s What is to be displayed SELECT SurnameFROM Table/s Tables the fields are to come

fromFrom Students

WHERE Operator, data The search criteria Where Gender=’F’ORDER BY Field/s Order in which the results are

displayed using sorting criteria of ASC (ascending) or DESC (descending)

ORDER BY Surname ASC

[ ] Field/s, table/s Used if field or table names include spaces of punctuation

Select [First Name]

Figure 6 Example of Query Language Syntax

Query by example (QBE)is a visual method for specifying a query. Often search criteria are entered into fields within what appears to be an empty record. It lists the fields and prompts and the operator enters the search conditions. Eg. The field postcode may be displayed and the user can enter “=2029” and the records meeting the criteria will be displayed.Operators are part of the query language. Relational operators are characters or symbols indicating the relationship between two expressions. Wildcard characters represent one ore more unknown characters. * represents any number of characters whereas a “?” substitutes for only one. Logical operators are used to combine queries so that a search is carried out on one ore more fields. AND requires both to be true, OR requires either the first or second query to be true.Type Operator Description ExampleRelational > Greater than A > B

>= Greater than or equal to A >= B< Less than A < B<= Less than or equal to A <= B= Equal to A = B<> Not equal to A <> BContains Expression contains criteria ABB contains ADoes not contain Expression does not contain criteria ABB does not contain

AIs blank Data entry in field is empty ‘Surname’ is blankIs not blank Data entry is present in field ‘Surname’ is not blankBegins with Data entry begins with criteria ‘Surname’ begins with

AEnds with Data entry ends with criteria ‘Surname’ ends with A

Logical AND Both expressions must be true A AND BOR At least one expression must be true A OR BNOT All expressions must be false A NOT B

Figure 7 Relational and Logical Operators Used To Build A Query Language

tools for hypermedia search and retrieval, including:–free text searching. A free text search is the same as using the Find command in a word

processor to locate a particular word or phrase in a document. Most web browsers have a Find command. The search is limited to the displayable text in the currently loaded web page It will not search through the metadata.

–operation of a search engine. A search engine is a program that builds an index of website content. Users can search the indexed content to locate relevant website content. This is different from a web directory which is purely created by humans based on submissions from users.

-indexing and search robots. An index is a table that contains information about the location of data. Search engines use automated software tools called search robots. These robots trawl the web and automatically locate and index individual web pages.

-metadata is data that defines or describes other data. Some search engines examine keywords specified within HTML metatags, whilst most determine their own keywords as they examine the content on each page. The simplest method for web page creators to add metadata as part of creating the page by using META tags (information inserted into the head area of your web pages. The head area is not seen by those viewing the web page.

describe the principles of the operation of a search engine. The general processes that search engines that crawl the web to compile and rank their indexed content include:

Crawling the web to locate and retrieve web pages- search robots retrieve web pages from web pages, extract any hyperlinks to other web pages and pass the complete web onto the indexer. Indexing and ranking each web page foundAnalysing search criteria entered by usersRetrieving suitably ranked web page results.

reporting on data found in hypermedia systems.

Other information processes for database information systems Displaying and collectingDisplaying is the information process that outputs information from an information system. Collecting is the information process that gathers data from the environment. It includes knowing what data is required, from where it will come and how it will be gathered. It is an input process and displaying is an output process. These two processes are the only two which directly interact with the users. The design of collection and display screens is critical as these are the user’s only window into the system.

–reporting on relevant information held in a database. The information from the database needs to be displayed to meet a specific purpose. A report is the formatted and organised presentation of data. These may include mailing labels, invoices. Before creating a report, the user

selects the required records using a query language and decides which fields need to be displayed. A typical report produced by a DBMS will include: a report header, a page header, details (the specifies fields from selected records), a page footer and a report footer. Different views of a database are created using a variety of forms. A form is used to enter, view and edit data. The layout of the form can be changes. A form must provide information to the user to ensure the accuracy and integrity of the database is maintained. In larger database systems different views of the data are made available to different users. The underlying record source for both forms and reports is built using SQL statements based on defined views of the database rather than raw tables. Eg in a hospital, administration staff cannot see doctor’s notes and doctors cannot see the patient’s financial records.

–constructing different views of a database for different purposes. Database forms are normally restricted to showing a singe record at a time but can be just as flexible in their layouts as reports. Like reports, forms are designed for a variety of purposes. Eg on form could give only the basic information about an employee whereas another could give everything including salary and deductions information according to what their purpose it. A form designer is a standard tool with a DBMS that gives you control over the layout and appearance of a database forms. It can be used as a prototyping tool for developing the data input and display screens fro a system.

Great data entry screens/forms can be used with minimal training. To achieve this, good design principles must be applied. Screen and report design principles:

Consistency of design—colour scheme, layout, typeface.Grouping of information- logically group related items and data togetherUse of white space- breaks up the screen into sections. Need not be white but should be a neutral colour that does not attract attention.Judicious use of colour and graphics- excessive use can distract usersLegibility of text

Additional screen design principles:Data validation- a check, at the time of data collection, to ensure the data is reasonable and meets certain criteriaEffective prompts- should accurately and concisely communicate a single simple message.

Issues related to information systems and databases acknowledgment of data sources. Data is protected by copyright regardless of where it is

obtained. Permission must be sought before the information can be used in a publication. The Copyright Act 2001 includes the replication and communication of all data types (text, number, images, video and audio) including the Internet, websites and written publications.

the Freedom of Information Act allows individuals to find out what data is being kept on them in both government and other organisations. However, there are some exemptions.

privacy principles. The collection of large amounts of data into centralised databases and the sharing of data between databases raise important questions about how private this information can remain secure. Pressure from external organisations/individuals has forced most organisations to adopt various ‘codes of practice’ to protect the privacy of individuals whose data they hold. Codes of practice may include:

There must be not information systems using personal data that are kept secret from the publicPeople have the right to inspect and correct data concerning them that is in IS’sPersonal information must not be used for any other purpose other than that for which it was collected (without prior consent)Only authorised people with a genuine need should be able to access and use any personal data.

quality of data. Accuracy of data is achieved by data validation which involves checking for data entry errors. Data Verification involves checking data for accuracy and integrity

accuracy of data and the reliability of data sources. Every database will contain errors like incorrect addresses, incorrect birth dates. Data can become incorrect or damaged.

access to data, ownership and control of data. It is an ethical problem if a single organisation or just a few worldwide corporations control access to large amount of data eg Google Earth. They effectively own the data and control our access to it.

data matching to cross link data across multiple databases (validate information retrieved from the Internet). Data found on the Internet should be verified with data in a book (if possible); if not possible, it should be verified with at least two other websites (that do not have the same source).

current and emerging trends in the organisation, processing, storage and retrieval of data. These include:

data warehousing: the collection and storage of large amounts of data from a range of sources, in order to support the future decisions of management. This data is often historic (business data from the previous years, for example) and is organised into a data warehouse. A data warehouse is a large separate combined copy of different databases used by an organisation. It includes historical data, which is used to analyse the activities of the organisation.data mining: This is a process of integrating large amounts of data, and by using specialised software, attempts to find hidden patterns in warehouse data. These previously unknown relationships among the data can be used to guide decision making and predict future behaviour patterns for example, retail companies can find customers with common interests, habits, etc., thus increasing potential marketing strategies. (the process of discovering non-obvious patterns within large collections of data).Online Analytical Processing (OLAP) and Online Transaction Processing (OLTP). Online analytical processing is a technique for providing business decision makers with statistical evidence, largely based on past trends, upon which they can make intelligent decisions. OLAP aims to provide this critical information visually, online, as needed and as quickly as possible. OLAP tools organise and combine multiple databases into multidimensional structures known as data cubes (however, it may have more than 3 dimensions).Databases that allow transactions to be processed immediately by remote users are known as online transaction processing systems . Completing an online purchase over the Internet is a common example of a transaction performed by an OLTP system. Such transactions must occur in close to real time. OLTP commonly involves many different database systems communicating to complete a single transaction. Eg. Internet purchase involves about 2 banks plus maybe PayPal as well as the seller’s system. Many OLTP systems include transaction monitoring software, whose central task is to direct, manage and control operation as they are performed by the various systems involved in each transaction.