Databases & The Internet Book 1 - Database Basics

8/8/2019 Databases & The Internet Book 1 - Database Basics

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DatabasesandTheInternet

Book1DatabaseBasics


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S4 Computing Databases & The Internet

1

Manual Databases

Data and Information

Remember that any fact or figure that is not organised or has no apparent meaning is known as data.

For example the number 393823 could be

A phone number

A map reference

A bank account number

An identification number

A code for a padlock

Once data has been processed it becomes information. E.g. Phone number: 393823.

This can be shown as:

What is a database?

A database is a collection of data about a single subject that is stored in a file. Data can either be stored

on paper or on a computer. A database that is stored on paper is known as a manual database.

Examples of manual databases:

Telephone directory

Pupil records stored on paper

The electoral roll

A database is made up of the following components:

File a collection of records about one topic

Record all the information about an item

Field a single piece of information about an item

Raw Data Processing Information

record

field


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What is an information system?

Just as information is defined as data which has been processed, an information system can be

described as a database or number of databases which are used be a company or individual to help

them make decisions. An information system that is stored on paper or card is known as a manual

information system.

Examples of manual information systems:

Newspapers or magazines focussing on a particular topic e.g. stock markets

Telephone directories of potential customers

Address books with staff contact details

Timetables for train routes in Scotland

Advantages of manual information systems:

You can carry the information with you

You dont need any expertise to use the system

A disadvantage of a manual information system is that it can be slow to find the information.


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Flat File Databases

What is a flat file database?

A database which is on a computer system is an electronic database. Simple electronic databases which

only contain one table in a single file are called flat file databases.

Examples of electronic databases:

Online telephone directory e.g.http://www.bt.com

School administration system Online property search engine e.g.

http://www.aspc.co.uk

What is an electronic information system?

An electronic information system is on a computer and stored on a backing storage device. People

need to be able to use the computer system to access the information.

Examples of electronic information systems:

Internal company directory of email addresses Regional library catalogue and booking system

Key advantages of electronic information systems:

It is quicker to search and therefore more efficient to use than a manual system You can store more information in a smaller physical space

Key disadvantages of electronic information systems:

You need to know how to use the computer system that contains the information You need to have a computer system


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Further advantages / disadvantages of electronic information systems

Computerised databases have fundamentally changed the way in which many organisations work.

Businesses or individuals now need to make use of a number of electronic databases to be able to:

compete in any business field perform medical research book a flight or a holiday get an MOT for your car send promotional material to potential customers order your grocery shopping online

The databases which support these electronic information systems are usually very large.

e.g. The information system used by the Driver and Vehicle Licensing Agency (DVLA) stores records

on around 40 million drivers and 30 million vehicles in the UK.

In the past manual databases worked well when the amount of data to be stored was small. Severe

problems arose when users needed to cross reference files. Electronic information systems solve these

problems.

Comparison: Grocery Shopping

Manual Online

You go to a supermarket with a list of items to buy.If the item is not in stock you might decide to go to

another supermarket or shop later to buy it. You

are responsible for taking the items off the

shelves, paying for them and delivering the items

to your home.

In this example the amount of data to be stored is

small. The stock levels in the supermarket could be

written down on a checklist.

5/8 6/8 7/8

Milk 16 12 4

Cheese 7 5 3

OJ 4 1 0

A problem with this system is that managers could

not easily see which customer bought which item,

so could not send them money off coupons for

items they regularly buy.

You visit the supermarkets website and choosefrom a database of available items. You then

enter your payment details and finally your

delivery address.

In this example the amount of data to be stored

is very large. This is due to the number of

customers and orders that are stored in the

electronic information system.

A manager can easily cross reference the files to

find out which customers buy the same item

regularly, if they pay in cash or by credit card,

etc. This information is very useful.


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Additional advantages of using electronic information systems are:

you can locate items of data quickly, cross referencing files you can make amendments easily, all occurrences can be changed at once data retrieved can be sorted into order quickly data analysis can be carried out automatically on search results computer reports containing calculations and summaries are produced quickly

Creating an electronic database

It is much easier to create a manual database as you do not have to worry about choosing field types. A

field type is the classification of a single piece of information in a record. As each character of text in acomputer system generally takes up 1 byte of storage space, field types are used to ensure that memory

is not wasted when storing other types of information such as numbers or images.

The key field types you should consider when creating your electronic database are:

Text Numeric Date Time

Graphic Calculated

Below is an example of a manual database record ... and the corresponding design

There are also more advanced field types which can be used:

Object - Suitable for all types of media including sound files, video and graphics Link Suitable for storing hyperlinks or URLs (web site addresses) up to 64000 characters long Boolean Holds the value true or false only

Field Name Field Type

Name Text

Age Numeric

Date Joined Date

Photo Graphic

Monthly Fee Numeric

Total Paid Calculated


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Databases and the Law

All data stored in an electronic database is automatically protected by the following laws:

Data Protection Act Computer Misuse Act Copyright, Design and Patents Act

Data Protection Act

If you are storing details about a person (or they are storing your details) then you need to be aware of

the Data Protection Act.

Data user the person or company storing the data e.g. the school office

Data subject the person who the data is about e.g. a pupil who has just joined the school

The data user must ensure they:

A data subject has the right to:

Computer Misuse Act

This act covers the use of computers to commit a crime, unauthorised access to computer material and

spreading viruses over the computer.

The following acts are an offence under the Computer Misuse Act:

Gaining unauthorised access to a computer system Making unauthorised changes to a computer system

are registered to hold data collect and use data legally only hold data for the purpose

required

keep data up to date

dont keep data longer than necessary give data subjects access to the

information stored about them

keep data secure

see the data stored about them (if they pay a fee) have incorrect data changed


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The act states that unauthorised changes to computer material includes:

Interfering with a computer system so it does not run properly e.g. changing hardware settings Making changes to the system to prevent others accessing it e.g. changing a password Making changes to the software stored on a computer system e.g. removing a program

Examples of computer misuse include:

Hacking This involves gaining access to computers which you should not have access to andthen changing, deleting or just looking at their files

Viruses creating and sending viruses Electronic Fraud This could involve using the computer to transfer money from a bank account

into your own account

With regard to electronic databases, hacking into a computer system to see or alter information or

transmitting a virus to destroy data would be an offence under the Computer Misuse Act.

Copyright, Designs and Patents Act

This act was introduced to try and protect companies and individuals whose work was being copied.

This work includes text, graphics, video and sound files.

The also covers computer software, it means that it is i llegal to copy software until 50 years after the

software was published.

It makes is illegal to attempt to:

Copy or steal software and software manuals Run software on your computer that does not have a license Use the Internet to upload or download software which you do not own

If found guilty of an offence under the Copyright, Designs and Patents Act:

that person can be sent to prison the owner of the software/material can sue for compensation

It is not just games and software packages that are protected by this law. If a database is stolen, copied

or uploaded to the Internet without permission from the copyright owner (the person who created the

database) that would be an offence under the Copyright, Design and Patents Act.


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Public / Private Information Systems

Private Information Systems

These are information systems that are not for public use.

For example:

Police National Database UK Government Tax Office DVLA (Driver and Vehicle Licensing Centre) Businesses (Tesco, Marks and Spencer, Topshop, Starbucks)

Public Information Systems

These are systems created for the public to help them find useful information.

For example:

Library Catalogue Newspapers Telephone Directories Train, Bus and Airline Timetables Media (teletext, news websites)

The key difference between private and public systems is everyone can access public systems whereas

access to private systems is limited. This is because if some of the information from a private system was

available to everyone it might be a threat to local or national security, or to a business profits.


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S4Computing Databases&TheInternet

11

FormsInbusinessnearlyalldataentry,editinganddeletingoperationsarecarriedoutviaforms.

Aformallowsyoutoviewandeditdatafromyourdatabaseinaslightlydifferentformat. Formsare

morepleasingtolookatandeasiertouse.

Theeasieritistoenterdataintoadatabase,thelesslikelyitismistakeswillbemade.

Aformnormallydisplaysonerecordonscreenatatime.

Levelsofaccesscanbeassignedtoaforme.g.thewholeformcanbemadereadonlyoronlycertain

textboxescanbemadereadonly. Thiswillstopdatabeingchangedbypeoplewhoarenotauthorised

toeditthedatabase.


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GoodFormDesignTipsTomakeyourdatabaseformsasuserfriendlyaspossibleyoushouldapplyasmanyofthetipslisted

belowtoyourformdesign.

F KeepfontsandcoloursconsistentO PlacethefieldsinalogicalorderR OnlyincluderelevantfieldsthatyouwanttheusertocompleteM MeaningfulinstructionsontheformhelpsyourusersS Usewhitespacetomakeiteasytounderstandandnavigate

Goodformdesignwillreducethenumber

ofproblemsdatabaseusershaveadjusting

fromamanualdatabasesystemtoan

electronicdatabasesystem.

Itenhancestheuserexperience.


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SearchingSimplesearchvsComplexsearchSearchingorQueryingthedatabaseisusedtofindinformation. Therearetwotypesofsearching:

SimpleSearch ComplexSearchThereisonecriteria/searchterme.g.Carterinthesurnamefield Thereistwoormorecriteria/searchtermse.g.Carterinthesurnamefieldand26intheagefield

OperatorsOperatorsthatcanbeusedforsearching:Operator Meaning Example Result> Greaterthan Fieldage>14 Findalltherecordsthathaveanagemore

than14


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QueriesWhen

you

need

to

find

aparticular

piece

of

data

in

your

database

you

have

to

create

aQuery.

You

must

enterkeywordsintothequerywindow,andthenthedatabasesoftwarewillSEARCHyourdatabaseto

findthedataaskedfor.

e.g.WhatisthephonenumberfortheSmashHittersVolleyballteam?

SearchonTeamNameforthedata=SmashHitters

Theresultofthesearchisthendisplayedinananswertable.

Thisis

an

example

of

asimple

query,

since

we

are

using

only

one

field

in

the

search.

Acomplexquerywouldrequireinputundermorethanonefieldheading,andcouldalsousemorethan

onetableinadatabase.

e.g. Howmanyredfordcarsarethereinstock?

Search on field Colour =Red AND

Search on field Make =Ford

e.g. Howmanygirlsinsixthyear?

Search on field Gender =F AND

Search on field Year =6


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WildcardsAwildcardisasymbolwhichisusedtostandforoneormorecharacterinthesearchcondition. Thisis

usefulifthewordsyouarelookingformightbeinthemiddleofalist,oryouarenotsureoftheexact

spellingofasurname. Youdonotusethe=signinthesearchcriteriaunlessyouknowexactlywhatyou

aresearchingfor.

Character Description Example Result* matchesanynumberof

characters

likewh*

like*beach*

what,where,when,white, etc

sandybeach,beachnearby, etc

? matches any single

character

b?ll bill,ball,bull,bell

[] matches any single

characterwithinthe[]

b[ae]ll ball,bell (notbillorbull)

! matches any single

characternotinthe[]

b[!ae]ll bill,bull

matches any one of a

rangeofcharacters

b[ac]d bad,bbd,bcd

~ matches any single

numericcharacter

1#3 103,113,123,133, etc

Anexampleofacomplexsearchusingwildcardswouldbe:HowmanyredFordcarswhichhavetheregistrationletterLarethere?

Search on field Colour =Red AND

Search on field Make =Ford AND

Search on field Registration like L*


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SortingSimplesortvComplexsortTherearetwotypesofsortinadatabase:

SimpleSortdatainthedatabaseissortedononefield.

(intheexampleabovesortedbyage)Complex

Sort

the

data

in

the

database

is

sorted

ontwoormorefields.

(intheexampleabovesortedbysurname,thenage)

Onceyouhavesuccessfullyqueriedthedatabaseitisoftenusefultoarrangetheinformationinsomekindoforder. Asortingoperationisperformedtoachievethis.

AscendingOrderAscendingorderiswhentheinformationissortedfromsmallesttobiggest,inthecaseofnumbers,orfromletterAtoletterZ.

DescendingOrderDescendingorderiswhentheinformationissortedfrombiggesttosmallest,inthe

caseofnumbers,orfromletterZtoletterA.


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Sorting:ExamplesForename Surname YearBilly McPherson 1David Farquhar 1Billy Irvine 1Ian Benholm 1Ian Shepherd 1

1.Sorttheabovelistoffirstyearpupilsalphabetically.

Sort on field Surname ascending

Forename Surname Exam %Billy Irvine 95Andrew McKenzie 87George Law 86Ian Benholm 84David Farquhar 77Scott Simpson 76

2.Sorttheabovelistofexamgradestoshowhighestmarksfirst.

Sort on field Exam % descending

Forename Surname Exam %Ian Shepherd 76Scott Simpson 76Jennifer Mackie 73Gary Kemp 67Suzanne McGregor 67Keith Gregory 64

3.Sorttheabovelistofexamgradestoshowhighestmarksfirst.Ifpupilshavethesamemarkthentheyshouldbeinalphabeticalorder.

Sort on field Exam % descending AND

Sort on field Surname ascending


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ReportsTypesofreportReportsarethenusedtodisplaytablesorresultsfromqueriesinamoreattractivemanner.Thetwomainreporttypesare:CARDFORMAT

Singlerecordpersection/page Lookslikeadatabaseform

LISTFORMAT

Multiplerecordspersection/page Lookslikeadatabasetable

Areportislikeaqueryinthatitcansummarisethedatainadatabase.Thekeydifferenceisthatreportsareusedtoproduceprintedoutput,notjustfindtheanswer.


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CreatingsimplereportsTheMicrosoftAccessreportgeneratorallowscontroloverlayout,shadings,fonts,styles,sizesandpagebreaks. Youcanalso:

Organiseandpresentyourdataingroups Calculaterunningtotals,grouptotalsandpercentagesoftotals Includesubreportsandgraphs Designanattractivepresentationformatwithpictures,linesandspecialfonts.

Areportismadeupofvarioussections,witheachonehavingaspecificpurpose.

Eachreportsectioncanberesizedasnecessary. Youshouldalwaystakecaretoensurethattitleanddataboxesareinline.

Reportheader/footer:containsinformationsuchasthetitle,authorand

Detailsection: containsthemainbodyofthereport

Pageheader/footer:containsinformationsuchascolumnheadingsand


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KeysIfdatabaseshavenotbeensetupcorrectlyproblemscanoccurlaterdowntheline.Takethisclassdatabaseforexample:

Forename Surname YearBilly McPherson 1David Farquhar 1Billy Irvine 1Ian Benholm 1Ian Shepherd 1

Ifanewpupil,alsocalledBillyIrvine,joinstheclassthiscouldcauseproblemswithexistingqueriesandreports.

PrimaryKeyWhendesigningyourdatabaseitiseasiertofindrecordsifyouuseaprimarykey.Theseareuniquevaluesthatidentifyeachindividualrecord.

Pupil ID Forename Surname Year001 Billy McPherson 1021 David Farquhar 1291 Billy Irvine 1054 Ian Benholm 1199 Ian Shepherd 1

Youdonotalwayshavetocreateanewdatabasefield,youcanuseexistingfieldsasprimarykeystoo.

Numeric IDs

are the best choice of keys


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ValidationValidationchecksareusedtotryandensurethatonlysuitabledataisenteredintothedatabase.Therearethreetypesofvalidationcheck:

PresenceCheck RangeCheck RestrictedChoice

PresenceCheckPresencecheckvalidationsetswhetherornotafieldcanbeleftblankornot.Forexample:PupilsregisteredwiththeSQAtosittheirexamsallmusthaveaScottishCandidateNumber.IfapresencecheckissetonthisfieldanyattempttoleavetheSCNentryblankwillcauseanerrormessagetoappear.

RestrictedChoiceRestrictedchoicevalidationlimitsthedatathatcanbeenteredintoafieldtoalistofvalues.Whendesigningthisyoumustlisttheacceptablevalues.(e.g.Computing,English,Maths)Forexample:PupilschoosingsubjectsforcolumnEwillonlyhaveacertainlistofsubjectoptions.Ifauserattemptstoenteranyothersubjectnameanerrormessagewillusuallyappear(althoughadvanceddatabaseuserscanchangethissetting).

RangeCheckRangecheckvalidationensuresthatthenumericdataenterediswithinacertainrangeofvalues.Whendesigningthisyoumuststatetheacceptablerangeofvalues.(e.g.>=12and

Databases & The Internet Book 1 - Database Basics

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