PHP外文翻译文献Word文档下载推荐.docx

PHP外文翻译文献Word文档下载推荐.docx

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:

connect（"

mysql:

//$db_username:

$db_password@$db_host/$db_database"

）;

Thesamebasicinformationispresentinbothcommands,butthePEARfunctionalsospecifiesthetypeofdatabasestowhichtoconnect.YoucanconnecttoMySQLorothersupporteddatabases.We’lldiscussbothconnectionmethodsindetail.

Inthischapter,you’lllearnhowtoconnecttoaMySQLserverfromPHP,howtousePHPtoaccessandretrievestoreddata,andhowtocorrectlydisplayinformationtotheuser.

TheProcess

Thebasicstepsofperformingaquery,whetherusingthemysqlcommand-linetoolorPHP,arethesame:

•Connecttothedatabase.

•Selectthedatabasetouse.

•BuildaSELECTstatement.

•Performthequery.

•Displaytheresults.

We’llwalkthrougheachofthesestepsforbothplainPHPandPEARfunctions.

Resources

WhenconnectingtoaMySQLdatabase,youwillusetwonewresources.Thefirstisthelinkidentifierthatholdsalloftheinformationnecessarytoconnecttothedatabaseforanactiveconnection.Theotherresourceistheresultsresource.Itcontainsallinformationrequiredtoretrieveresultsfromanactivedatabasequery’sresultset.You’llbecreatingandassigningbothresourcesinthischapter.

QueryingtheDatabasewithPHPFunctions

Inthissection,weintroducehowtoconnecttoaMySQLdatabasewithPHP.It’squitesimple,andwe’llbeginshortlywithexamples,butweshouldtalkbrieflyaboutwhatactuallyhappens.WhenyoutryconnectingtoaMySQLdatabase,theMySQLserverauthenticatesyoubasedonyourusernameandpassword.PHPhandlesconnecting

tothedatabaseforyou,anditallowsyoutostartperformingqueriesandgatheringdataimmediately.

AsinChapter8,we’llneedthesamepiecesofinformationtoconnecttothedatabase:

•TheIPaddressofthedatabaseserver

•Thenameofthedatabase

•Theusername

•Thepassword

Beforemovingon,makesureyoucanlogintoyourdatabaseusingtheMySQLcommand-lineclient.

Figure9-1showshowthestepsofthedatabaseinteractionrelatetothetwotypesofresources.BuildingtheSELECTstatementhappensbeforethethirdfunctioncall,butitisnotshown.It’sdonewithplainPHPcode,notaMySQL-specificPHPfunction.

Figure9-1.Theinteractionbetweenfunctionsandresourceswhenusingthedatabase

IncludingDatabaseLoginDetails

You’regoingtocreateafiletoholdtheinformationforloggingintoMySQL.Storingthisinformationinafileyouincludeisrecommended.Ifyouchangethedatabasepassword,thereisonlyoneplacethatyouneedtochangeit,regardlessofhowmany

PHPfilesyouhavethataccessthedatabase.

Youdon’thavetoworryaboutanyonedirectlyviewingthefileandgettingyourdatabaselogindetails.Thefile,ifrequestedbyitself,isprocessedasaPHPfileandreturnsablankpage.

Troubleshootingconnectionerrors

Oneerroryoumaygetis:

Fatalerror:

Calltoundefinedfunctionmysql_connect（）inC:

\ProgramFiles\Apache

SoftwareFoundation\Apache2.2\htdocs\db_test.phponline4

ThiserroroccursbecausePHP5.xforWindowswasdownloaded,andMySQLsupportwasnotincludedbydefault.Tofixthiserror,copythephp_mysql.dllfilefromtheext/directoryofthePHPZIPfiletoC:

\php,andthenC:

\WINDOWS\php.ini.

Makesuretherearetwolinesthatarenotcommentedoutbyasemicolon（;

）atthebeginningofthelinelikethese:

extension_dir="

c:

/PHP/ext/"

extension=php_mysql.dll

ThiswillchangetheextensiontoincludethedirectorytoC:

/phpandincludetheMySQLextension,respectively.YoucanusetheSearchfunctionofyourtexteditortocheckwhetherthelinesarealreadythereandjustneedtobeuncommented,orwhethertheyneedtobeaddedcompletely.

You’llneedtorestartApache,andthenMySQLsupportwillbeenabled.

SelectingtheDatabase

Nowthatyou’reconnected,thenextstepistoselectwhichdatabasetousewiththemysql_select_dbcommand.Ittakestwoparameters:

thedatabasenameand,optionally,thedatabaseconnection.Ifyoudon’tspecifythedatabaseconnection,thedefaultistheconnectionfromthelastmysql_connect:

//Selectthedatabase

$db_select=mysql_select_db（$db_database）;

if（!

$db_select）

{

die（"

Couldnotselectthedatabase:

<

br/>

"

.mysql_error（））;

}

Again,it’sgoodpracticetocheckforanerroranddisplayiteverytimeyouaccessthedatabase.

Nowthatyou’vegotagooddatabaseconnection,you’rereadytoexecuteyourSQLquery.

BuildingtheSQLSELECTQuery

BuildingaSQLqueryisaseasyassettingavariabletothestringthatisyourSQLquery.Ofcourse,you’llneedtouseavalidSQLquery,orMySQLreturnswithanerrorwhenyouexecutethequery.Thevariablename$queryisusedsincethenamereflectsitspurpose,butyoucanchooseanythingyou’dlikeforavariablename.TheSQLqueryinthisexampleisSELECT*FROMbooks.

Youcanbuildupyourqueryinpartsusingthestringconcatenate（.）operator:

ExecutingtheQuery

Tohavethedatabaseexecutethequery,usethemysql_queryfunction.Ittakestwoparameters—thequeryand,optionally,thedatabaselink—andreturnstheresult.Savealinktotheresultsinavariablecalled,youguessedit,$result!

Thisisalsoagoodplacetocheckthereturncodefrommysql_querytomakesurethattherewerenoerrorsinthequerystringorthedatabaseconnectionbyverifyingthat$resultisnotFALSE:

Whenthedatabaseexecutesthequery,alloftheresultsformaresultset.Theseresultscorrespondtotherowsthatyousawupondoingaqueryusingthemysqlcommand-lineclient.Todisplaythem,youprocesseachrow,oneatatime.

FetchingandDisplaying

Usemysql_fetch_rowtogettherowsfromtheresultset.Itssyntaxis:

arraymysql_fetch_row（resource$result）;

Ittakestheresultyoustoredin$resultfromthequeryasaparameter.Itreturnsonerowatatimefromthequeryuntiltherearenomorerows,andthenitreturnsFALSE.Therefore,youdoaloopontheresultofmysql_fetch_rowanddefinesomecodetodisplayeachrow:

Thecolumnsoftheresultrowarestoredinthearrayandcanbeaccessedoneatatime.Thevariable$result_row[2]accessesthesecondattribute（asdefinedinthequery’scolumnorderorthecolumnorderofthetableifSELECT*isused）intheresultrow.

Fetchtypes

Thisisnottheonlywaytofetchtheresults.Usingmysql_fetch_array,PHPcanplacetheresultsintoanarrayinonestep.Ittakesaresultasitsfirstparameter,andthewaytobindtheresultsasanoptionalsecondparameter.IfMYSQL_ASSOCisspecified,theresultsareindexedinanarraybasedontheircolumnnamesinthequery.IfMYSQL_NUMisspecified,thenthenumberstartingatzeroaccessestheresults.Thedefaultvalue,MYSQL_BOTH,returnsaresultarraywithbothtypes.Themysql_fetch_

associsanalternativetosupplyingtheMYSQL_ASSOCargument.

ClosingtheConnection

Asaruleofthumb,youalwayswanttocloseaconnectiontoadatabasewhenyou’redoneusingit.Closingadatabasewithmysql_closewilltellPHPandMySQLthatyounolongerwillbeusingtheconnection,andwillfreeanyresourcesandmemoryallocatedtoit:

mysql_close（$connection）

Installing

PEARusesaPackageManagerthatoverseeswhichPEARfeaturesyouinstall.

WhetheryouneedtoinstallthePackageManagerdependsonwhichversionofPHPyouinstalled.Ifyou’rerunningPHP4.3.0ornewer,it’salreadyinstalled.Ifyou’rerunningPHP5.0,PEARhasbeensplitoutintoaseparatepackage.TheDBpackagethatyou’reinterestedinisoptionalbutinstalledbydefaultwiththePackageManager.SoifyouhavethePackageManager,you’reallset.

Unix

YoucaninstallthePackageManageronaUnixsystembyexecutingthefollowing

fromtheshell（command-line）prompt:

lynx-sourcehttp:

//go-pear.org/|php

Thistakestheoutputofthego-pear.orgsite（whichisactuallythesourcePHPcode）toinstallPEARandpassesitalongtothephpcommandforexecution.

Windows

ThePHP5installationincludesthePEARinstallationscriptasC:

\php\go-pear.bat.Incaseyoudidn’tinstallallthefilesinChapter2,goaheadandextractallthePHPfilestoC:

/phpfromthecommandprompt,andexecutethe.batfile.

Creatingaconnectinstance

TheDB.phpfiledefinesaclassoftypeDB.RefertoChapter5formoreinformationonworkingwithclassesandobjects.We’llprincipallybecallingthemethodsintheclass.TheDBclasshasaconnectmethod,whichwe’lluseinsteadofouroldconnectfunctio