通过php访问mysql

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1、原文： GettingPHPtoTalktoMySQlNowthatyou’recomfortableusingtheMySQLclienttoolstomanipulatedatainthedatabase,youcanbeginusingPHPtodisplayandmodifydatafromthedatabase.PHPhasstandardfunctionsforworkingwiththedatabase.First,we’regoingtodiscussPHP’sbuilt-indatabasefunctions.We’llalsoshowyouhowtous

2、etheThePHPExtensionandApplicationRepository(PEAR)databasefunctionsthatprovidetheabilitytousethesamefunctionstoaccessanysupporteddatabase.Thistypeofflexibilitycomesfromaprocesscalledabstraction.Inprogramminginterfaces,abstractionsimplifiesacomplexinteraction.Itworksbyremovinganynonessential

3、partsoftheinteraction,allowingyoutoconcentrateontheimportantparts.PEAR’sDBclassesareonesuchdatabaseinterfaceabstraction.Theinformationyouneedtologintoadatabaseisreducedtothebareminimum.ThisstandardformatallowsyoutointeractwithMySQL,aswellasotherdatabasesusingthesamefunctions.Similarly,othe

4、rMySQL-specificfunctionsarereplacedwithgenericonesthatknowhowtotalktomanydatabases.Forexample,theMySQL-specificconnectfunctionis:mysql_connect($db_host,$db_username,$db_password);versusPEAR’sDBconnectfunction:$connection=DB::connect("mysql://$db_username:$db_password@$db_host/$db_database"

5、);Thesamebasicinformationispresentinbothcommands,butthePEARfunctionalsospecifiesthetypeofdatabasestowhichtoconnect.YoucanconnecttoMySQLorothersupporteddatabases.We’lldiscussbothconnectionmethodsindetail.Inthischapter,you’lllearnhowtoconnecttoaMySQLserverfromPHP,howtousePHPtoaccessandretrie

6、vestoreddata,andhowtocorrectlydisplayinformationtotheuser.1TheProcessThebasicstepsofperformingaquery,whetherusingthemysqlcommand-linetoolorPHP,arethesame:•Connecttothedatabase.•Selectthedatabasetouse.•BuildaSELECTstatement.•Performthequery.•Displaytheresults.We’llwalkthrougheachofthesestep

7、sforbothplainPHPandPEARfunctions.2ResourcesWhenconnectingtoaMySQLdatabase,youwillusetwonewresources.Thefirstisthelinkidentifierthatholdsalloftheinformationnecessarytoconnecttothedatabaseforanactiveconnection.Theotherresourceistheresultsresource.Itcontainsallin