Premier press PHP essentials 2nd edition

PHPEssentials,Second
Edition
ISBN:1931841349
byJulieC.
Meloni
PremierPress©2003(326pages)
Thistextservesasan
introductiontothePHP
scriptinglanguageand
providesreal-worldexamples
ofcommonuses--from
downloading,installingand
configuringaWebserver
withPHP,tocreating
dynamiccontentvia
databaseinterfacesand
more.
TableofContents BackCover
TableofContents
PHPEssentials,SecondEdition
Introduction
Chapter1 - GettingStartedwithPHP
Chapter2 - BasicPHPTechniques
Chapter3 - WorkingwithDatabases
CreatingandPopulating
Chapter4 DatabaseTables
Chapter5 - UserAuthentication
UserTrackingand
Chapter6 -

SessionManagement
AdvancedPHP
Chapter7 - Techniques:Web-Based
DatabaseAdministration
AdvancedPHP
Chapter8 - Techniques:Workingwith
Images
AdvancedPHP
Chapter9 - Techniques:Workingwith
XML
EssentialPHPLanguage
AppendixA Reference
AppendixB - GettingSupport
Index
ListofFigures
ListofTables



PHPEssentials,Second
Edition
ISBN:1931841349
byJulieC.
Meloni
PremierPress©2003(326pages)
Thistextservesasan
introductiontothePHP
scriptinglanguageand
providesreal-worldexamples
ofcommonuses--from

downloading,installingand
configuringaWebserver
withPHP,tocreating
dynamiccontentvia
databaseinterfacesand
more.
TableofContents

BackCover

BackCover
DiveintotheneweditionofthispopularguidetoPHP.
Withatruefocusontheessentials,thisbookgivesyou
thesolidfoundationinPHPprogrammingyou’re
lookingfor.Andyoudon’thavetobeacomputer
scientistorprogrammertolearnfromit!Thesimple,
learn-by-exampleformatofPHPEssentialswillallow
youtoquicklyusethepowerofPHPtodevelop
successful,dynamicWebsites.


LearnFaster
StartwithPHPbasicslikeparsing,workingwith
arrays,anddisplayingdynamiccontent
UsePHPtoplananddisplayane-commerce
productcatalogandtoensuresafeandsecure
shopping
MasteradvancedPHPgraphicstechniquessuchas
creatingnewimagesandscalingexistingimages
InstallaWebserver—forWindowsorLinux—and

adddatabasesupport
LearnMore
Learnhowtoestablishvariousdatabase
connectionswithPHP,includingMySQL,
PostgreSQL,andOracle
UsePHPtocreateadatabasetableandedityour
data
Masterusertrackingandsessionmanagement
techniques
UsethePHPLanguageReferencetoansweryour
questionsaboutsyntax,variables,built-in
functions,andmore!
AbouttheAuthor
JulieC.Meloniisthetechnicaldirectorfori2i
interactive—amultimediacompanylocatedinLos
Altos,California.Sheisalsotheauthorofseveral
booksandarticlesonWeb-basedprogramming
languagesanddatabasetopics,includingthefirst
editionofPHPEssentialsfromPremierPress.








PHPEssentials,SecondEdition
JulieMeloni

Copyright©2003byPremierPress,adivisionofCourseTechnology.
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ThePremierPresslogoandrelatedtradedressaretrademarksof
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PHPwaswrittenbythePHPDevelopmentTeam,andreleasedunderthe
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Acknowledgments
ThanksasalwaystothePHPGroup,ZendTechnologies,theApache
SoftwareFoundationandMySQLABforcreatingandmaintainingsuch
wonderfulandaccessibleproductsforallusers.
ThankstoeverysinglePHPuseranddeveloper,becausewithoutyou,I
wouldn'thaveanythingtowriteabout.
Enormousthankstoeveryoneati2iInteractive,fortheirnever-ending
supportandencouragement.
AbouttheAuthor
JULIEMELONIisthetechnicaldirectorfori2iInteractive,amultimedia
companylocatedinLosAltos,California.She'sbeendevelopingWebbasedapplicationssincetheWebfirstsawthelightofdayand
rememberstheexcitementsurroundingthefirstGUIWebbrowser.Sheis
theauthorofseveralbooksandarticlesonWeb-basedprogramming
languagesanddatabasetopics,andyoucanfindtranslationsofherwork
inmanydifferentlanguages,includingChinese,Danish,Finnish,Italian,
Portuguese,PolishandevenSerbian.







Introduction
IfyoucomparethisbooktomostoftheotherbooksonPHP,you'llquickly
noticethatthisbookismuchsmallerthanthosethousand-page
behemoths.Therelativesmallnessofthisbookisintentional-I'vefound
it'seasiertolearnfromabookyoucanactuallyhold!
Thatbeingsaid,plentyoftopicsthatarecoveredinthoselengthierbooks
arenotcoveredinthisbook.Thisbookoffers,asitstitle,saysthe

essentialinformation.Inotherwords,informationthatwillprovideasolid
foundationfortheadditionaltopicsyouwillfindinlonger,moreadvanced
books.
Amaincharacteristicofthisbook,besidesteachingthefundamentals,is
thatyoudon'thavetobeacomputerscientistorprogrammertolearn
fromit.Ifyouareacomputerscientistorprogrammeralready,youmay
notliketheratherprosaicnatureoftheexplanationsandinstructionsin
thisbook.Ultimately,Iwantedtowriteabookthatsomeonecouldtakeoff
theshelf,skimthrough,andsay,"Hey,thisPHPthinglookslikeaneat
language,andever-so-easytolearn!"Becauseitis!
Ifyou'vebeenprogrammingwithPHPsincethebeginningoftime,there's
probablynotmuchyoucangetoutofthisbook,excepttohandittoyour
bossandsay,"Look!Anotherbookonwhatawonderfullanguagethisis.
CanwepleasestopusingASP/ColdFusion/Java/Perl/C++andmigrate
toPHP?"Butifyou'vejustdabbledwithPHPorhaveneverseenaPHP
script,Iamcertainthisbookwillbeofsomeusetoyou.


SupplementalWebSite
Additionalinformationforthisbook(andforotherbooksI'vewritten)can
befoundatAtthissiteyoucandownloadall
thecodesamplesinthisbook,aswelladditionaltutorialsand
notificationsofanyerrorsinthebook.Youcanalsousethesitetoget
helpwithanyproblemsyoumayhavewiththeexamples.

GettingStartedwithPHP
Whetheryou'reafirst-timeprogrammeroryouhaveafewyearsofWeb
applicationdevelopmentunderyourbelt,you'llfindsomethingusefulin
thisbook.Hopefully,whatyou'llfindisasimple"learn-by-example"path
todevelopingsuccessfuldynamicWebsites.
UnliketheWebitself,thisbookisfairlylinear.You'llstartbyinstallingthe
softwareneededtousePHP,andthenyou'llgraduallymoveinto"Hello
World!"scriptsandeventuallycreateshoppingcartsandotherdatabasedrivenapplications.
IfyouhaveanaccountwithanInternetServiceProviderwhohas
enabledtheuseofPHPforallusersontheserver,youcanskipaheadto
Chapter2.ButasyoucaninstallfreelyavailableWebservers,PHP,and
adatabsseortwoonyourownmachine-withalittlepokingandproddingIrecommendyoudoso.It'sagreatwaytolearnthe"guts"ofthetools
you'llbeusing.







WhatIsPHP?
PHPisaserver-sidescriptinglanguage.WhenyourWebbrowser
accessesaURL,itismakingarequesttoaWebserver.Ifyouare
requestingaPHPpage,somethinglike
theWebserverwakesupthe
PHPparsingengineandsays,"Hey!You'vegottodosomethingbeforeI
sendaresultbacktothisperson'sWebbrowser."ThePHPparsing
enginerunsthroughthePHPcodefoundinthehome.phpfileandreturns
theresultingoutput.ThisoutputispassedbacktotheWebserverasthe

HTMLcodeinthedocument,whichinturnispassedontoyourbrowser,
whichdisplaysittoyou.

ABriefHistoryofPHP
In1994,anincrediblyforward-thinkingmannamedRasmusLerdorf
developedasetoftoolsthatusedaparsingenginetointerpretafew
macroshereandthere.Theywerenotextravagant:aguestbook,a
counter,andsomeother"homepage"elementsthatwerecoolwhenthe
Webwasinitsinfancy.Heeventuallycombinedthesetoolswithaform
interpretation(FI)packagehehadwritten,addedsomedatabase
support,andreleasedwhatwasknownasPHP/FI.
Then,inthespiritofOpenSourcesoftwaredevelopment,developersall
overtheworldbegancontributingtoPHP/FI.By1997,morethan50,000
WebsiteswereusingPHP/FItoaccomplishdifferenttasks-connectingto
adatabase,displayingdynamiccontent,andsoon.
Atthatpoint,thedevelopmentprocessreallystartedbecomingateam
effort.WithprimaryassistancefromdevelopersZeevSuraskiandAndi
Gutmans,theversion3.0parserwascreated.ThefinalreleaseofPHP3
occurredinJuneof1998,whenitwasupgradedtoincludesupportfor
multipleplatforms(it'snotjustforLinuxanymore!)andWebservers,
numerousdatabases,andSNMP(SimpleNetworkManagement
Protocol)andIMAP(InternetMessageAccessProtocol).
AfterPHP3.0wasreleased,theaforementionedSuraskiandGutmans
begantodevelopasuper-fastenginetoreplacethecoreelementsof


PHP,andinmid-1999theZendEnginewasborn.PHP4.0wasbasedon
thisengine,andwasreleasedintheSpringof2000.Thisreleasewasa
watershedforPHP-thevastamountofnewfeatuesandincresed
performanceresultsnowfoundinPHP4.0madeitaviabletoolfor

advancedWebapplicationdevelopment.ThecurrentversionisPHP4.3,
whichyou'lllearntoinstallinChapter1,"GettingStartedwithPHP."
Inthethreeyearsbetweentheappearance,inearly2000,ofthefirst
editionofthisbookandthisnewestedition,PHPusagehasexploded.
CompanieslikeAmazon.comandYahoo!usePHPinvariousareasof
theirWebsites.That'sdefinitelyhighpraise!Themostrecentsurveyfrom
Netcraft(showPHPisinstalledonover9.5
milliondomains.ItiscommonplaceforInternetServiceProviderstooffer
PHPandMySQLineventhemostbasic(orfree!)hostingpackages,and
PHPsourcecodeisshippedwithmostLinuxdistributions.
Additionally,therearehundredsofbookswhichaddressPHP
developmentinsomeway-amarkedincreasefromthefiveorsowhich
wereavailablewhenthefirsteditionofthisbookwaspublished.Thetens
ofthousandsofdeveloperswhouseandcontributetoPHPhavemade
thissimplelanguagenear-revolutionary,andthosenumberscontinueto
grow.

WhatDoesPHPDo?
PHPdoesanythingyouwant,exceptsitonitsheadandspin.Actually,
withalittleon-the-flyimagemanipulationandDynamicHTML,itcan
probablydothat,too.
AccordingtothePHPManual,"ThegoalofthelanguageistoallowWeb
developerstowritedynamicallygeneratedpagesquickly."
ThelistbelowshowsomecommonusesofPHP.Thisisbynomeansa
completelist,anddoesn'tindicateanyofthemoreadvancedfunctionality
thatdevelopersuseinlargeapplications;it'sjustanideaoftheitemsthat
youraveragedevelopermayuseonadailybasis.
Performsystemfunctions:create,open,readfrom,writeto,and

closefilesonyoursystem,executesystemcommands,create
directories,andmodifypermissions.
Gatherdatafromforms:savethedatatoafile,senddataviaemail,returnmanipulateddatatotheuser.
Accessdatabasesandgeneratecontenton-the-fly,orcreatea
Webinterfaceforadding,deleting,andmodifyingelementswithin
yourdatabase.
Setcookiesandaccesscookievariables.
UsePHPuserauthenticationtorestrictaccesstosectionsofyour
Website.
Createimageson-the-fly.
Encryptdata.

ANoteRegardingOpenSourceDevelopment
OpenSourcesoftwaremustfollowthesecriteria(theyareavailablein
detailat />Freeredistribution.
Theprogrammustincludesourcecodeandmustallow
distributioninsourcecodeaswellascompiledform.
Thelicensemustallowmodificationsandderivedworks.
Integrityoftheauthor'ssourcecode.
Nodiscriminationagainstpersonsorgroups.
Nodiscriminationagainstfieldsofendeavor.
Distributionoflicense.
Licensemustnotbespecifictoaproduct.


Licensemustnotcontaminateothersoftware.
PHPisafineexampleofOpenSourcedevelopmentanddistribution.
Otherexamplesincludethefollowing:
Apache.TheWebServerofchoiceformorethan4.8millionWeb
sites.

Linux.Theoperatingsystemofchoiceformorepeoplethan
Microsoftwouldhaveyouthink.
BIND.ThesoftwareprovidingDomainNameServicestothe
Internet-allofit.
Sendmail.Themostwidely-usedsoftwarefortransportinge-mail
fromsendertorecipient.
Synonymouswith"OpenSource"is"volunteerism."Developers
contributingtoOpenSourcesoftwaredon'tdirectlymakemoneyfrom
doingso.Whereverpossible,contributetoyourfavoriteOpenSource
organization,beitthePHPGrouporsomeoneelse.Givebacksometime
byansweringquestions,helpingwithdocumentation,contributingcode
wherepossible,orevenmakingamonetarydonation.Thecostof
equipment,connectivity,tools,and,mostimportantly,brainpoweris
absorbeddirectlybythevolunteerdeveloper,sothatyouandIhavea
freely(andwidely)availablepieceofsoftware.







IsPHPRightforMe?
OnlyyoucandecideifPHPshouldbeyourlanguageofchoice,whether
you'redevelopingsitesforpersonalorcommercialuseonasmallor
largescale.Icanonlytellyouthatinthecommercialrealm,I'veworked
withallthepopularserver-sidescriptinglanguages-ActiveServerPages
(ASP),ColdFusion,JavaServerPages(JSP),Perl,andPHP-on
numerousplatformsandvariousWebservers,withvariousdegreesof
success.PHPistherightchoiceforme:it'sflexible,fast,andsimplisticin

itsrequirementsyetpowerfulinitsoutput.
BeforedecidingwhethertousePHPinalarge-scaleorcommercial
environment,consideryouranswerstothefollowingquestions:
WillyoualwaysusethesameWebserverhardwareand
software?Ifnot,lookforsomethingcross-platformandavailable
formultipleWebservers:PHP.
Willyoualwayshavetheexactsamedevelopmentteam,
comprisedentirelyofASP(orColdFusion)developers?Orwill
youusewhoeverisavailable,thusnecessitatingalanguagethat
iseasytolearnandsyntacticallysimilartoCandPerl?Ifyou
havereasontobelievethatyourASPorColdFusiondevelopers
mightdropoffthefaceoftheearth,don'tusethosetools;use
PHP.
Arememoryandserverloadanissue?Ifso,don'tusebloated
third-partysoftwarethatleakspreciousmemory;usePHP.
Thereareplentyofotherquestionstoaskyourselfwhenmakinga
decisionregardingadevelopmentlanguage,andinshortIcanonlysay
"Tryit,you'lllikeit!"







Chapter1:GettingStartedwithPHP
ThischapterwillwalkyouthroughthebasicsofgettingPHPandaWeb
serverupandrunningonyoursystem,andwillshowyouhowtoadd
databasesupportaswell.Youmayormaynotneedtoreadthisentire
chapter-ifyoudon'tplantoinstallMicrosoftIIS,then,don'tworryabout

readingthatsection.
Nomatterwhatsectionorsectionsyouchoosetoread,pleasepayclose
attentiontotheinstructionsgiven.Theinstallationisnotdifficult,butitis
importanttofollowthestepsclosely.Missingoneinstructionwillresultin
frustrationonyourpartandangrye-mailsinmyinbox,bothofwhichI'd
liketoavoid!


InstallingaWebServer
Inthissection,you'lllearntoinstallApacheonLinux/UNIXorWindows,
andyou'llalsolearnthebasicsofgettingandinstallingotherWeb
servers,suchasMicrosoftIIS.Personally,Ineverinstallanythingother
thanApache,evenifit'sonmypersonalWindowsmachines.Butifyou
wanttoinstallMicrosoftIISoranotherWebserver,feelfree!Someother
Webserverswillbediscussedattheendofthissection.
ThroughouttheApacheinstallationsections,theinstructionsassumeyou
knowthebasicsofadministeringeitherLinux/UNIXorWindows.Ifyou
don'tknowanythingaboutthecommandline,orhaveneverloggedonas
AdministratortoaWindowsmachine,youshouldtakeastepbackand
brushuponyoursystemadministratorskillsbeforecontinuing.

WorkingwithApache
TheApacheWebserverisanopen-sourceprojectproducedand
maintainedbytheApacheSoftwareFoundation.Since1996,Apachehas
beenthemostpopularWebserverinuseontheInternet-quitearun!
Apachecurrentlyholdsover60percentoftheWebservermarketshare,
andtherearenosignsofitrelinquishingitsstronghold.
ThecurrentversionoftheApacheserveris2.0.44,whichistheversion
usedasthebasisfortheinstallationinstructionsinthischapter.Should
youpurchasethisbookandfindthecurrentversionisdifferent,firsttry

theinstructionsaswrittenhere,andthencheckforupdatedinstructions
atthisbook'sWebsite,Unlesssomething
drastichashappenedtotheApachesourcecode(orthisbookisyears
outofdate),theinstallationinstructionsinthisbookwillworkdespite
minorversionchanges.
WhenworkingwithApache,youhavetwooptionsforinstallation:building
fromsourceorinstallingfromapre-compiledbinary.Buildingfromsource
givesyouthegreatestflexibility,asitenablesyoutoremovemodulesyou
don'tneedandextendtheserverwiththird-partymodules.Additionally,


buildingfromsourceenablesyoutoeasilyupgradetothelatestversions
andquicklyapplysecuritypatches,whereasupdatedversionsfrom
vendorscantakedaysorweekstoappear.
Pre-compiledbinaryinstallationsareavailablefromthird-partyvendors
andcanalsobedownloadedfromtheApacheSoftwareFoundationWeb
site.ThisinstallationmethodprovidesasimplewaytoinstallApachefor
userswithlimitedsystemadministrationknowledgeorwithnospecial
configurationneeds.
Inthefollowingsections,you'llusethebuild-from-sourcemethodfor
installationonLinux/UNIXandthepre-compiledinstallationmethod(in
thiscase,usinganInstaller)forWindowssystems.

InstallingandConfiguringApacheonLinux/UNIX
Inthissection,you'llinstallafreshbuildofApache2.0onLinux/UNIX.
TheofficialApachedownloadpageislocatedat
anditwillalwaysclearlyindicate
themostrecentversionofApacheforyourplatform.
TheApachesourcedistributionfilesarefirstpackedwiththetarutility
andthencompressed,eitherwiththegziptoolorthecompressutility.

Downloadthe.tar.gzversionifyouhavethegunziputilityinstalledin
yoursystem,anddownloadthetar.Zfileifgunzipisnotpresentinyour
system.
Thefileyouwanttodownloadwillbenamedsomethinglikehttpd2.0.version.tar.gzorhttpd-2.0.version.tar.Z,whereversionisthemost
recentreleaseversionofApache.Forexample,Apacheversion2.0.44is
downloadedasafilenamedhttpd-2.0.44.tar.gzorhttpd-2.0.44.tar.Z.
Whicheverfileyoudownload,putitindirectoryreservedforsourcefiles,
suchas/usr/src/or/usr/local/src/.
Now,let'sgetonwiththeinstalling.Ifyoudownloadedthetarball
compressedwithgzip,uncompressandunpackthesoftwarebytyping
thefollowingcommandattheprompt(#):
#gunzip