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Project2OnlineVotingSystemSchoolofSoftware,ChengduPolytechnicLecturer:MuQichunTask7VotingofLoginUser
ProgrammingVotingcouldonlyberealizedafterlogin.Therefore,wecouldformulateafilechecklogin.phptojudgewhethertheloginissuccessful.Addthisfiletotheuserprofilemodificationpageandthevotingpage,soonlytheloginusercouldconducttheprofilemodificationandthevoting.Everysuccessfulvotingneedtwoinfomodificationoftwodatatables.Firstly,add1inthecarnumofcarinfo.Secondly,recordthedetailsofthisvoteinthevotedetailtable.Thesetwooperationsaresynchronous,therefore,thetransactionmechanismofthedatabasemustbeusedtorealizeandguaranteethesetwosynchronousoperationsofthedatabases.
TransactionMechanismItmeanstotransferthedatabasefromonestatustoanother.Whenthedatabasesubmitsthework,it’sguaranteedthatallmodificationshavebeensavedornot.Therearefourcharacteristics,i.e.,atomicity,consistency,isolationanddurability.ThistransactioncouldbeconstitutedbyonesimpleSQLsentenceoragroupofcomplicatedsentences.It’saprogramimplementationunittoaccessorupdatethedataitemsinsidethedatabase.Theoperationintheaffairiseithertomodifyordonothing.Thisisthetargetofthetransaction.It’sverysimpletousetheMySQLaffairmechanisminphp:usemysqli_autocommit($conn,0)toclosetheautomaticsubmitting,normallyperformmultipleSQLsentences,andrespectivelyjudgetheresultofeverySQLsentence.Incaseofanimplementationfailure,usemysqli_rollback($conn)torollback/cancelalloperations,otherwise,usemysqli_commit($conn)tosubmittheoperationnormally.
SampleCodeThetransactionmechanismcodeisverysimple.Inthefollowingexample,shutdowntheautomaticsubmitting,addtworecordsintheIPdatatable,andthenrespectivelydeterminewhethertheimplementationeverytimeissuccessful.Ifalloperationsaresucce
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