翻译文献-sqlite数据库

外文原文SQLITENAMEDPARAMETERSTHETHIRDPARAMETERBINDINGMETHODISUSINGNAMEDPARAMETERSWHEREASYOUCANASSIGNYOUROWNNUMBERSUSINGNUMBEREDPARAMETERS,YOUCANASSIGNALPHANUMERICNAMESWITHNAMEDPARAMETERSLIKEWISE,ASNUMBEREDPARAMETERSAREPREFIXEDWITHAQUESTIONMARK,YOUIDENTIFYNAMEDPARAMETERSBYPREFIXINGACOLONTOTHEPARAMETERNAMECONSIDERTHEFOLLOWINGCODESNIPPETTAKENFROMPARAMETERSCNAME“MACKINAWPEACHES“SQL“INSERTINTOEPISODESID,CID,NAMEVALUESCOSMO,COSMO,NEWMAN“RCSQLITE3_PREPAREDB,SQL,STRLENSQL,SQLITE3_BIND_INTSTMT,SQLITE3_BIND_PARAMETER_INDEXSTMT,“COSMO“,10SQLITE3_BIND_TEXTSTMT,SQLITE3_BIND_PARAMETER_INDEXSTMT,“NEWMAN“,NAME,STRLENNAME,SQLITE_TRANSIENTSQLITE3_STEPSTMTSQLITE3_FINALIZESTMTTHISEXAMPLEISIDENTICALTOTHEPREVIOUSEXAMPLEUSINGNUMBEREDPARAMETERS,EXCEPTITUSESTWONAMEDPARAMETERSCALLEDCOSMOANDNEWMANINSTEADLIKEPOSITIONALPARAMETERS,NAMEDPARAMETERSAREAUTOMATICALLYASSIGNEDNUMBERSBYSQLITE3_PREPAREWHILETHENUMBERSASSIGNEDTOEACHPARAMETERAREUNKNOWN,YOUCANRESOLVETHEMUSINGSQLITE3_BIND_PARAMETER_INDEX,WHICHTAKESAPARAMETERNAMEANDRETURNSTHECORRESPONDINGPARAMETERNUMBERTHISISTHENUMBERYOUUSETOBINDTHEVALUETOITSPARAMETERALLINALL,NAMEDPARAMETERSMAINLYHELPWITHLEGIBILITYMORETHANANYTHINGELSEPARAMETERINDEXESWHILETHEFUNCTIONSQLITE3_BIND_PARAMETER_INDEXSEEMSTOREFERTOAPARAMETERNUMBERASANINDEX,FORALLINTENTSANDPURPOSESTHETWOTERMSNUMBERANDINDEXARESYNONYMOUSIHAVESETTLEDONTHETERMNUMBERRATHERTHANINDEXFORPARAMETERPOSITIONSASARESULTOFSOMEDISCUSSIONONTHESQLITEMAILINGLIST,WHICHHASSUGGESTEDTHATNUMBERISPERHAPSABETTERDESCRIPTIONTHETERMINDEXWASUSEDWHENPARAMETERBINDINGWASLIMITEDONLYTOPOSITIONALPARAMETERSWITHTHEADDITIONOFNUMBEREDPARAMETERS,REFERRINGTOPARAMETERPOSITIONSASSEQUENTIALINDEXESCANBESOMEWHATMISLEADINGTCLPARAMETERSTHEFINALPARAMETERSCHEMEISCALLEDTCLPARAMETERSANDISSPECIFICMORETOTHETCLEXTENSIONTHANITISTOTHECAPIBASICALLY,ITWORKSIDENTICALLYTONAMEDPARAMETERSEXCEPTTHATRATHERTHANUSINGALPHANUMERICVALUESFORPARAMETERNAMES,ITUSESTCLVARIABLENAMESINTHETCLEXTENSION,WHENTHETCLEQUIVALENTOFSQLITE3_PREPAREISCALLED,THETCLEXTENSIONAUTOMATICALLYSEARCHESFORTCLVARIABLESWITHTHEGIVENPARAMETERNAMESINTHEACTIVETCLPROGRAMENVIRONMENTANDBINDSTHEMTOTHEIRRESPECTIVEPARAMETERSDESPITEITSCURRENTAPPLICATIONINTHETCLINTERFACE,NOTHINGPROHIBITSTHISSAMEMECHANISMFROMBEINGAPPLIEDTOOTHERLANGUAGEINTERFACES,WHICHCANINTURNIMPLEMENTTHESAMEFEATUREINTHISRESPECT,REFERRINGTOTHISPARAMETERMETHODSOLELYASTCLPARAMETERSMAYBEABITOFAMISNOMERTHETCLEXTENSIONJUSTHAPPENEDTOBETHEFIRSTAPPLICATIONTHATUTILIZEDTHISMETHODBASICALLY,THETCLPARAMETERSYNTAXDOESLITTLEMORETHANPROVIDEANALTERNATESYNTAXTONAMEDPARAMETERSRATHERTHANPREFIXINGTHEPARAMETERSWITHACOLON,ITUSESADOLLARSIGNERRORSANDTHEUNEXPECTEDUPTONOW,WEHAVELOOKEDATTHEAPIFROMARATHEROPTIMISTICVIEWPOINT,ASIFNOTHINGCOULDEVERGOWRONGBUTTHINGSDOGOWRONG,ANDTHEREISAPARTOFTHEAPIDEVOTEDTOTHATTHETHREETHINGSYOUALWAYSHAVETOGUARDAGAINSTINYOURCODEAREERRORS,BUSYCONDITIONS,ANDMYPERSONALFAVORITESCHEMACHANGESHANDLINGERRORSMANYOFTHEAPIFUNCTIONSRETURNINTEGERRESULTCODESTHATMEANSTHEYCANPOTENTIALLYRETURNERRORCODESOFSOMESORTTHEMOSTCOMMONFUNCTIONSTOWATCHARETYPICALLYTHEMOSTFREQUENTLYUSED,SUCHASSQLITE3_OPEN,SQLITE3_PREPAREANDFRIENDS,ASWELLASSQLITE3_EXECYOUSHOULDALWAYSPROGRAMDEFENSIVELYANDREVIEWEVERYAPIFUNCTIONDOCUMENTEDINAPPENDIXBBEFOREYOUUSEITTOENSURETHATYOUDEALWITHEVERYPOSSIBLEERRORCONDITIONTHATCANARISETHEREAREABOUT23DIFFERENTERRORSDEFINEDINTHEAPIONLYAFRACTIONOFTHEMWILLREALLYMATTERTOYOURAPPLICATIONINPRACTICEALLOFTHESQLITERETURNCODESARELISTEDINTABLE62ALLOFTHEAPIFUNCTIONSTHATCANRETURNTHEMARELISTEDASFOLLOWSSQLITE3_BIND_XXXSQLITE3_CLOSESQLITE3_CREATE_COLLATIONSQLITE3_COLLATION_NEEDEDSQLITE3_CREATE_FUNCTIONSQLITE3_PREPARESQLITE3_EXECSQLITE3_FINALIZESQLITE3_GET_TABLESQLITE3_OPENSQLITE3_RESETSQLITE3_STEPSQLITE3_TRANSFER_BINDINGSYOUCANGETEXTENDEDINFORMATIONONAGIVENERRORUSINGSQLITE3_ERRMSG,WHICHISDECLAREDASFOLLOWSCONSTCHARSQLITE3_ERRMSGSQLITE3ITTAKESACONNECTIONHANDLEASITSONLYARGUMENTANDRETURNSTHEMOSTRECENTERRORRESULTINGFROMANAPICALLONTHATCONNECTIONIFNOERRORHASBEENENCOUNTERED,ITRETURNSTHESTRING“NOTANERROR”TABLE62SQLITERETURNCODESCODEDESCRIPTIONSQLITE_OKTHEOPERATIONWASSUCCESSFULSQLITE_ERRORGENERALSQLERRORORMISSINGDATABASEITMAYBEPOSSIBLETOOBTAINMOREERRORINFORMATIONDEPENDINGONTHEERRORCONDITIONSQLITE_SCHEMA,FOREXAMPLESQLITE_PERMACCESSPERMISSIONDENIEDCANNOTREADORWRITETOTHEDATABASEFILESQLITE_ABORTACALLBACKROUTINEREQUESTEDANABORTSQLITE_BUSYTHEDATABASEFILEISLOCKEDSQLITE_LOCKEDATABLEINTHEDATABASEISLOCKEDSQLITE_NOMEMACALLTOMALLOCHASFAILEDWITHINADATABASEOPERATIONSQLITE_READONLYANATTEMPTWASMADETOWRITETOAREADONLYDATABASESQLITE_INTERRUPTOPERATIONWASTERMINATEDBYSQLITE3_INTERRUPTSQLITE_IOERRSOMEKINDOFDISKI/OERROROCCURREDSQLITE_CORRUPTTHEDATABASEDISKIMAGEISMALFORMEDTHISWILLALSOOCCURIFANATTEMPTISMADETOOPENANONSQLITEDATABASEFILEASASQLITEDATABASESQLITE_FULLINSERTIONFAILEDBECAUSETHEDATABASEISFULLTHEREISNOMORESPACEONTHEFILESYSTEMORTHEDATABASEFILECANNOTBEEXPANDEDSQLITE_CANTOPENSQLITEWASUNABLETOOPENTHEDATABASEFILESQLITE_PROTOCOLTHEDATABASEISLOCKEDORTHEREHASBEENAPROTOCOLERRORSQLITE_EMPTYINTERNALONLYTHEDATABASETABLEISEMPTYSQLITE_SCHEMATHEDATABASESCHEMAHASCHANGEDSQLITE_CONSTRAINTABORTDUETOCONSTRAINTVIOLATIONTHISCONSTANTISRETURNEDIFTHESQLSTATEMENTWOULDHAVEVIOLATEDADATABASECONSTRAINTSUCHASATTEMPTINGTOINSERTAVALUEINTOAUNIQUEINDEXTHATALREADYEXISTSINTHEINDEXSQLITE_MISMATCHDATATYPEMISMATCHANEXAMPLEOFTHISISANATTEMPTTOINSERTNONINTEGERDATAINTOACOLUMNLABELEDINTEGERPRIMARYKEYFORMOSTCOLUMNS,SQLITEIGNORESTHEDATATYPEANDALLOWSANYKINDOFDATATOBESTOREDBUTANINTEGERPRIMARYKEYCOLUMNISONLYALLOWEDTOSTOREINTEGERDATASQLITE_MISUSELIBRARYWASUSEDINCORRECTLYTHISERRORMIGHTOCCURIFONEORMOREOFTHESQLITEAPIROUTINESISUSEDINCORRECTLYEXAMPLESOFINCORRECTUSAGEINCLUDECALLINGSQLITE3_EXECAFTERTHEDATABASEHASBEENCLOSEDUSINGSQLITE3_CLOSEORCALLINGSQLITE3_EXECWITHTHESAMEDATABASEPOINTERSIMULTANEOUSLYFROMTWOSEPARATETHREADSSQLITE_NOLFSUSESOSFEATURESNOTSUPPORTEDONHOSTTHISVALUEISRETURNEDIFTHESQLITELIBRARYWASCOMPILEDWITHLARGEFILESUPPORTLFSENABLEDBUTLFSISNTSUPPORTEDONTHEHOSTOPERATINGSYSTEMSQLITE_AUTHAUTHORIZATIONDENIEDTHISOCCURSWHENACALLBACKFUNCTIONINSTALLEDUSINGSQLITE3_SET_AUTHORIZERRETURNSSQLITE_DENYSQLITE_ROWSQLITE3_STEPHASANOTHERROWREADYSQLITE_DONESQLITE3_STEPHASFINISHEDEXECUTINGWHILEITISVERYUNCOMMONOUTSIDEOFEMBEDDEDSYSTEMS,ONEOFTHEMOSTCRITICALERRORSYOUCANENCOUNTERISSQLITE_NOMEM,WHICHMEANSTHATNOMEMORYCANBEALLOCATEDONTHEHEAPEG,MALLOCFAILEDNORMALLY,AFTERASINGLEMALLOCCALLFAILS,THESQLITELIBRARYREFUSESTOFUNCTIONALLMAJORCALLSCANRETURNSQLITE_NOMEMIFTHEAPPLICATIONISABLETORECOVERFROMANOUTOFMEMORYCONDITION,ITMAYSTILLBEPOSSIBLETORESTORETHESTATEOFTHESQLITELIBRARYUSINGSQLITE3_GLOBAL_RECOVER,WHICHISDECLAREDASFOLLOWSINTSQLITE3_GLOBAL_RECOVERTHISFUNCTIONRESTORESTHELIBRARYSTATESOTHATITCANBEUSEDAGAINYOUMUSTFINALIZEORRESETALLACTIVESTATEMENTSSQLITE3_STMTPOINTERSBEFORECALLINGTHISFUNCTIONOTHERWISEITWILLRETURNSQLITE_BUSYTHISFUNCTIONWILLALSORETURNSQLITE_ERRORIFYOUAREUSINGANYINMEMORYDATABASES,EITHERASAMAINORTEMPTHETEMPDATABASEISWHERETEMPORARYDATAISSTOREDSEEATTACHDATABASEINAPPENDIXAFORDETAILSINEITHERCASE,SQLITEWILLNOTRESETTHELIBRARYANDITWILLREMAINUNUSABLECAUTIONSQLITE3_GLOBAL_RECOVERISNOTTHREADSAFECALLINGITFROMWITHINATHREADEDAPPLICATIONWHENTHREADSOTHERTHANTHECALLERHAVEUSEDSQLITEISDANGEROUSANDWILLALMOSTCERTAINLYRESULTINMALFUNCTIONSSQLITEINCLUDESMEMORYMANAGEMENTFUNCTIONSSPECIFICALLYFORTHREADSTHESEARECOVEREDLATERINTHESECTION“THREADSANDMEMORYMANAGEMENT”THESQLITE3_GLOBAL_RECOVERFUNCTIONISAIMEDATEMBEDDEDAPPLICATIONSWHEREMEMORYISSCARCERTHANNORMALAPPLICATIONSITCANBEOMITTEDFROMSQLITEATCOMPILETIMEBYDEFININGTHESQLITE_OMIT_GLOBALRECOVERPREPROCESSORDIRECTIVEHANDLINGBUSYCONDITIONSTWOIMPORTANTFUNCTIONSRELATEDTOPROCESSINGQUERIESARESQLITE3_BUSY_HANDLERANDSQLITE3_BUSY_TIMEOUTIFYOURPROGRAMUSESADATABASEONWHICHTHEREAREOTHERACTIVECONNECTIONS,ODDSAREITWILLEVENTUALLYHAVETOWAITFORALOCK,ANDTHEREFOREWILLHAVETODEALWITHSQLITE_BUSYWHENEVERYOUCALLANAPIFUNCTIONTHATCAUSESSQLITETOSEEKALOCKANDSQLITEISUNABLETOGETIT,THEFUNCTIONWILLRETURNSQLITE_BUSYTHEREARETHREEWAYSTODEALWITHTHISHANDLESQLITE_BUSYYOURSELF,EITHERBYRERUNNINGTHESTATEMENTORTAKINGSOMEOTHERACTIONHAVESQLITECALLABUSYHANDLERASKSQLITETOWAITBLOCKORSLEEPFORSOMEPERIODOFTIMEFORTHELOCKTOCLEARTHELASTOPTIONINVOLVESUSINGSQLITE3_BUSY_TIMEOUTTHISFUNCTIONTELLSSQLITEHOWLONGTOWAITFORALOCKTOCLEARBEFORERETURNINGSQLITE_BUSYWHILEITCANULTIMATELYRESULTINYOUSTILLHAVINGTOHANDLESQLITE_BUSY,INPRACTICESETTINGTHISVALUETOASUFFICIENTPERIODOFTIMESAY30SECONDSUSUALLYPROVIDESENOUGHTIMEFOREVENTHEMOSTINTENSIVETRANSACTIONTOCOMPLETENEVERTHELESS,YOUSHOULDSTILLHAVESOMECONTINGENCYPLANINPLACETOHANDLESQLITE_BUSYUSERDEFINEDBUSYHANDLERSTHESECONDOPTIONENTAILSUSINGSQLITE3_BUSY_HANDLERTHISFUNCTIONPROVIDESAWAYTOCALLAUSERDEFINEDFUNCTIONRATHERTHANBLOCKINGORRETURNINGSQLITE_BUSYRIGHTAWAYITSDECLAREDASFOLLOWSINTSQLITE3_BUSY_HANDLERSQLITE3,INTVOID,INT,VOIDTHESECONDARGUMENTISAPOINTERTOAFUNCTIONTOBECALLEDASTHEBUSYHANDLER,ANDTHETHIRDARGUMENTISAPOINTERTOAPPLICATIONSPECIFICDATATOBEPASSEDASTHEFIRSTARGUMENTTOTHEHANDLERTHESECONDARGUMENTTOTHEBUSYHANDLERISTHENUMBEROFPRIORCALLSMADETOTHEHANDLERFORTHESAMELOCKSUCHAHANDLERMIGHTCALLSLEEPFORAPERIODTOWAITOUTTHELOCK,ORITMAYSENDSOMEKINDOFNOTIFICATIONITMAYDOWHATEVERYOULIKE,ASITISYOURSTOIMPLEMENTBEWARNED,THOUGH,THATREGISTERINGABUSYHANDLERDOESNOTGUARANTEETHATITWILLALWAYSBECALLEDASMENTIONEDINCHAPTER5,SQLITEWILLFOREGOCALLINGABUSYHANDLERFORACONNECTIONIFITPERCEIVESADEADLOCKMIGHTRESULTSPECIFICALLY,IFYOURCONNECTIONINSHAREDISINTERFERINGWITHANOTHERCONNECTIONINRESERVED,SQLITEWILLNOTINVOKEYOURBUSYHANDLER,HOPINGYOUWILLTAKETHEHINTINTHISCASE,YOUARETRYINGTOWRITETOTHEDATABASEFROMSHAREDSTARTINGTHETRANSACTIONWITHBEGINWHENYOUREALLYSHOULDBESTARTINGFROMRESERVEDSTARTINGTHETRANSACTIONWITHBEGINIMMEDIATETHEONLYRESTRICTIONONBUSYHANDLERSISTHATTHEYMAYNOTCLOSETHEDATABASECLOSINGTHEDATABASEFROMWITHINABUSYHANDLERCANDELETECRITICALDATASTRUCTURESOUTFROMUNDERTHEEXECUTINGQUERYANDRESULTINCRASHINGYOURPROGRAMADVICEALLTHINGSCONSIDERED,THEBESTROUTEMAYBETOSETTHETIMEOUTTOAREASONABLEVALUEANDTHENTAKESOMEPRECAUTIONIFANDWHENYOURECEIVEASQLITE_BUSYVALUEINGENERAL,IFYOUAREGOINGTOWRITETOTHEDATABASE,STARTINRESERVEDIFYOUDONTDOTHIS,THENTHENEXTBESTTHINGISTOINSTALLABUSYHANDLER,SETTHETIMEOUTTOAKNOWNVALUE,ANDIFSQLITERETURNSSQLITE_BUSY,CHECKTHERESPONSETIMEIFTHETIMEISLESSTHANTHEBUSYHANDLERSDELAY,THENSQLITEISTELLINGYOUTHATYOURQUERYANDCONNECTIONISPREVENTINGAWRITERFROMPROCEEDINGIFYOUWANTTOWRITETOTHEDATABASEATTHISPOINT,YOUSHOULDFINALIZEORRESET,THENREEXECUTETHESTATEMENT,THISTIMESTARTINGWITHBEGINIMMEDIATEHANDLINGSCHEMACHANGESWHENEVERACONNECTIONCHANGESTHEDATABASESCHEMA,ALLOTHERPREPAREDSTATEMENTSTHATWERECOMPILEDBEFORETHECHANGEAREINVALIDATEDTHERESULTISTHATTHEFIRSTCALLTOSQLITE3_STEPFORSUCHSTATEMENTSRETURNSSQLITE_ERRORFROMALOCKINGSTANDPOINT,THESCHEMACHANGEOCCURSBETWEENTHETIMEAREADERCALLSSQLITE3_PREPARETOCOMPILEASTATEMENTANDCALLINGSQLITE3_STEPTOEXECUTEITWHENTHISHAPPENS,THEONLYCOURSEOFACTIONFORYOUISTOFINALIZEORRESETTHEQUERYANDSTARTOVERHOWEVER,YOUMUSTCONFIRMTHATTHEERRORISINFACTDUETOASCHEMACHANGETODOSO,WHENEVERSQLITE3_STEPRETURNSSQLITE_ERROR,YOUSHOULDCALLSQLITE3_RESETTOSEEIFITRETURNSSQLITE_SCHEMAANOTHERWAYTOCHECKFORTHISCONDITIONISTOCALLSQLITE3_EXPIRED,WHICHTAKESTHESTATEMENTHANDLEASITSONLYARGUMENTNOTEITSIMPORTANTTHATYOUUNDERSTANDTHATWHENASCHEMACHANGEOCCURS,SQLITE3_STEPNEVERRETURNSSQLITE_SCHEMADIRECTLYITALWAYSRETURNSSQLITE_ERRORYOUTHENHAVETOCALLSQLITE3_FINALIZE,SQLITE3_RESET,ORSQLITE3_EXPIREDTODETERMINEIFTHEERRORWASDUETOSQLITE_SCHEMAYOUSHOULDALWAYSCHECKFORTHISCONDITIONWHENEVERYOUUSESQLITE3_STEPSEVERALEVENTSCANCAUSESQLITE_SCHEMAERRORSDETACHINGDATABASESMODIFYINGORINSTALLINGUSERDEFINEDFUNCTIONSORAGGREGATESMODIFYINGORINSTALLINGUSERDEFINEDCOLLATIONSMODIFYINGORINSTALLINGAUTHORIZATIONFUNCTIONSVACUUMINGTHEDATABASETHEREASONTHESQLITE_SCHEMACONDITIONEXISTSULTIMATELYRELATESTOTHEVDBEWHENACONNECTIONCHANGESTHESCHEMA,OTHERCOMPILEDQUERIESMAYHAVEVDBECODETHATPOINTSTODATABASEOBJECTSTHATNOLONGEREXIST,ORAREINADIFFERENTLOCATIONINTHEDATABASERATHERTHANRUNNINGTHERISKOFABIZARRERUNTIMEERRORLATER,SQLITEINVALIDATESALLSTATEMENTSTHATHAVEBEENCOMPILEDBUTNOTEXECUTEDTHEYMUSTBERECOMPILEDSQLITE_SCHEMACANONLYOCCURONTHEFIRSTCALLTOSQLITE3_STEPTHISISBECAUSESQLITE3_STEP,WHENSUCCESSFUL,ALWAYSGETSALOCKONTHEDATABASEONCEYOUHAVEALOCKONTHEDATABASE,ITISIMPOSSIBLEFORANYOTHERCONNECTIONTOWRITETOORALTERTHEDATABASESOIFTHEFIRSTCALLISSUCCESSFUL,YOUAREGUARANTEEDTHATALLSUBSEQUENTCALLSTOSQLITE3_STEPWILLNOTENCOUNTERSQLITE_SCHEMAONEPOSSIBLEWAYPROVIDEDBYTHESQLITEFAQTOHANDLESQLITE_SCHEMAISSHOWNINLISTING68LISTING68HANDLINGSQLITE_SCHEMAINTRCSQLITE3_STMTPSTMTCHARZSQL“SELECT“DO/COMPILETHESTATEMENTFROMSQLASSUMESUCCESS/SQLITE3_PREPAREPDB,ZSQL,1,WHILESQLITE_ROWSQLITE3_STEPPSTMT/DOSOMETHINGWITHTHEROWOFAVAILABLEDATA/FINALIZETHESTATEMENTIFASQLITE_SCHEMAERRORHASOCCURRED,THENTHEABOVECALLTOSQLITE3_STEPWILLHAVERETURNEDSQLITE_ERRORSQLITE3_FINALIZEWILLRETURNSQLITE_SCHEMAINTHISCASETHELOOPWILLEXECUTEAGAIN/RCSQLITE3_FINALIZEPSTMTWHILERCSQLITE_SCHEMAAPOSSIBLEVARIATIONISTOTAKEINTOCONSIDERATIONBOUNDPARAMETERSTHESEPARAMETERSCANBEAUTOMATICALLYTRANSFERREDTOTHENEWCOMPILEDQUERYUSINGSQLITE3_TRANSFER_BINDINGS,ASSHOWNINLISTING69LISTING69HANDLINGSQLITE_SCHEMAWITHSQLITE3_TRANSFER_BINDINGSINTRC,PROCESSED,SKIPSQLITE3_STMTPSTMTNULLSQLITE3_STMTPLASTSTMTNULLCHARZSQL“SELECT“DOSQLITE3_PREPAREPDB,ZSQL,1,/IFTHEREWASALASTSTMT,TRANSFERBINDINGSFROMIT/IFPLASTSTMTNULLSQLITE3_TRANSFER_BINDINGSPLASTSTMT,PSTMT/KEEPTRACKOFTHECURRENTSTMT/PLASTSTMTPSTMTWHILESQLITE_ROWSQLITE3_STEPPSTMT/DOSOMETHINGWITHTHEROWOFAVAILABLEDATA/PROCESSEDRCSQLITE3_FINALIZEPSTMTWHILERCSQLITE_SCHEMAANOTHEROPTIONFORCHECKINGFORSQLITE_SCHEMAWITHOUTFINALIZINGDESTROYINGTHEQUERYISTOCALLSQLITE3_RESETINSTEADOFSQLITE3_FINALIZETHISWILLPROVIDEYOUWITHTHESQLITE_SCHEMAERRORIFITEXISTSHOWEVER,IFTHEERRORISNOTSCHEMARELATED,YOUAVOIDTHECOSTOFHAVINGTORECOMPILETHEQUERYSINCESQLITE3_RESETLEAVESTHEQUERYINASTATEWHEREITCANSTILLBEEXECUTEDTRACINGSQLIFYOUAREHAVINGAHARDTIMEFIGURINGOUTEXACTLYWHATYOURPROGRAMISDOINGWITHTHEDATABASE,YOUCANTRACKWHATSQLSTATEMENTSITHASEXECUTEDUSINGSQLITE3_TRACEITSDECLARATIONISASFOLLOWSVOIDSQLITE3_TRACESQLITE3,VOIDXTRACEVOID,CONSTCHAR,VOIDTHISFUNCTIONISANALOGOUSTOPUTTINGAWIRETAPONACONNECTIONYOUCANUSEITTOGENERATEALOGFILEOFALLSQLEXECUTEDONAGIVENCONNECTIONASWELLPROVIDEHELPFULDEBUGGINGINFORMATIONEVERYSQLSTATEMENTTHATISPROCESSEDISPASSEDTOTHECALLBACKFUNCTIONSPECIFIEDINTHESECONDARGUMENTSQLITEPASSESTHEDATAPROVIDEDINTHETHIRDARGUMENTOFSQLITE3_TRACETOTHEFIRSTARGUMENTOFTHECALLBACKFUNCTIONOPERATIONALCONTROLTHEAPIPROVIDESSEVERALFUNCTIONSYOUCANUSETOMONITORAND/ORMANAGESQLCOMMANDSATCOMPILETIMEANDRUNTIMETHESEFUNCTIONSALLOWYOUTOINSTALLCALLBACKFUNCTIONSWITHWHICHTOMONITORANDCONTROLVARIOUSDATABASEEVENTSASTHEYHAPPENCOMMITHOOKSTHESQLITE3_COMMIT_HOOKFUNCTIONALLOWSYOUTOMONITORWHENTRANSACTIONSCOMMITONAGIVENCONNECTIONITISDECLAREDASFOLLOWSVOIDSQLITE3_COMMIT_HOOKSQLITE3CNX,/DATABASEHANDLE/INTXCALLBACKVOIDDATA,/CALLBACKFUNCTION/VOIDDATA/APPLICATIONDATA/THISFUNCTIONREGISTERSTHECALLBACKFUNCTIONXCALLBACK,WHICHWILLBEINVOKEDWHENEVERATRANSACTIONCOMMITSONTHECONNECTIONGIVENBYCNXTHETHIRDARGUMENTDATAISAPOINTERTOAPPLICATIONSPECIFICDATA,WHICHSQLITEPASSESTOTHECALLBACKFUNCTIONIFTHECALLBACKFUNCTIONRETURNSANONZEROVALUE,THENTHECOMMITISCONVERTEDINTOAROLLBACKPASSINGANULLVALUEINFORTHECALLBACKFUNCTIONEFFECTIVELYDISABLESTHECURRENTLYREGISTEREDCALLBACKIFANYALSO,ONLYONECALLBACKCANBEREGISTEREDATATIMEFORAGIVENCONNECTIONTHERETURNVALUEFORSQLITE3_COMMIT_HOOKISNULLUNLESSANOTHERCALLBACKFUNCTIONWASPREVIOUSLYREGISTERED,INWHICHCASETHEPREVIOUSDATAVALUEISRETURNEDNOTETHESQLITE3_COMMIT_HOOKFUNCTIONISCURRENTLYMARKEDASEXPERIMENTALANDISTHEREFORESUBJECTTOCHANGEHOWEVER,ACCORDINGSQLITESAUTHOR,THISISEXTREMELYUNLIKELYASTHISFUNCTIONHASBEENINTHEAPIFORSOMETIMENOWROLLBACKHOOKSROLLBACKHOOKSARESIMILARTOCOMMITHOOKSEXCEPTTHATTHEYWATCHFORROLLBACKSFORAGIVENCONNECTIONROLLBACKHOOKSAREREGISTEREDWITHTHEFOLLOWINGFUNCTIONVOIDSQLITE3_ROLLBACK_HOOKSQLITE3CNX,VOIDXCALLBACKVOIDDATA,VOIDDATATHISFUNCTIONREGISTERSTHECALLBACKFUNCTIONXCALLBACK,WHICHWILLBEINVOKEDINTHEEVENTOFAROLLBACKONCNX,WHETHERBYANEXPLICITROLLBACKCOMMANDORANIMPLICITERRORORCONSTRAINTVIOLATIONTHECALLBACKISNOTINVOKEDIFATRANSACTIONISAUTOMATICALLYROLLEDBACKDUETOTHEDATABASECONNECTIONBEINGCLOSEDTHETHIRDARGUMENTDATAISAPOINTERTOAPPLICATIONSPECIFICDATA,WHICHSQLITEPASSESTOTHECALLBACKFUNCTIONASINSQLITE3_COMMIT_HOOK,EACHTIMEYOUCALLSQLITE3_ROLLBACK_HOOK,THENEWCALLBACKFUNCTIONYOUPROVIDEWILLREPLACEANYCURRENTLYREGISTEREDCALLBACKFUNCTIONIFACALLBACKFUNCTIONWASPREVIOUSLYREGISTERED,SQLITE3_ROLLBACK_HOOKRETURNSTHEPREVIOUSDATAARGUMENT中文翻译SQLITE数据库1命名参数第三个参数约束方法是使用命名参数。然而你可以用你的号码作为编号的参数，你能够用命名参数代替字母数字名称。同样，作为编号的参数前缀一个问号（），你确定以参数名用前缀一个冒号（）来命名参数。考虑如下代码片断（摘自PARAMETERSC）NAME“MACKINAWPEACHES“SQL“INSERTINTOEPISODESID,CID,NAMEVALUESCOSMO,COSMO,NEWMAN“RCSQLITE3_PREPAREDB,SQL,STRLENSQL,SQLITE3_BIND_INTSTMT,SQLITE3_BIND_PARAMETER_INDEXSTMT,“COSMO“,10SQLITE3_BIND_TEXTSTMT,SQLITE3_BIND_PARAMETER_INDEXSTMT,“NEWMAN“,NAME,STRLENNAME,SQLITE_TRANSIENTSQLITE3_STEPSTMTSQLITE3_FINALIZESTMT除了使用两个命名参数所谓COSMO和NEWMAN代替,这个例子使用编号为参数与前面的例子完全相同像定位参数，命名参数均由SQLITE3_PREPARE（）自动分配号码。而号码分配给每个参数都是未知，你用SQLITE3_BIND_PARAMETER_INDEX（）也解决不了它们，其中一个参数的名称并返回相应的参数号码。用这个数约束它的值及其参数。总而言之，命名参数，主要是帮助易读性比任何事情都重要。11参数指标而功能SQLITE3_BIND_PARAMETER_INDEX（），似乎是指一个参数数目作为指数，对所有意图和目的两个条款（编号和索引）是同义的。我已解决了对任期内有多少，而不是指数为参数的立场，由于一些论SQLITE消息名单中，曾建议若干或许是一个更好的描述。任期指数时所用的参数约束力是有限的，只定位参数。由于增加了编号为参数，是指参数的位置（顺序）指标，可以有误导成分。12TCL参数最后参数计划名为TCL的参数和方法是具体多向延伸的TCL比是给C的指数。基本上，它的工程，以相同的命名参数除外，而不是比用字母数字值为参数的名字，它使用的TCL变数名称。在TCL扩建中，当SQLITE3_PREPARE的TCL同等学历被命名，方法自动延长搜寻的TCL变量与特定的参数的名字在活跃的TCL计划环境约束，他们以各自的参数。尽管其目前的应用方法接口，没有禁止这种同样的机制被应用于其他语言接口，这反过来可以实施相同的功能。在这方面，是指这参数法仅仅作为TCL参数可能是一个有点名不副实。方法刚刚扩建正好是第一个应用程序，利用此方法。基本上，函数参数语法多提供一个备用的语法来命名参数，而不是PREFIXING参数，以冒号（），它是用美元符号（）。13错误和意外现在到为止，我们看到空气污染指数从较为乐观的角度来看，好像没有什么能够去错了。但事情发生错误，并有一部分TEMP指数，专门讨论了这一点。三件事情，你总是要防范在你的代码是错误的，忙条件，并以我个人最爱模式转变。14异常处理很多的API函数返回整数的结果代码。这意味着他们有可能返回错误代码的某种形式。最常见的功能，以观赏通常是最常使用，像这样SQLITE3_OPEN（）,SQLITE3_PREPARE（）ANDFRIENDS,ASWELLASSQLITE3_EXEC（）你要始终保护程序，并检查每一个API函数（记录在附录B）之前，你用它来确保您对付所有可能的误差，条件是有可能发生的。现时大约有23个不同的错误界定，在可用函数中。只有一小部分，他们真的会事您在实践中的应用。所有的SQLITE返回码列在表62。所有的API函数可以返回他们列举如下SQLITE3_BIND_XXX（）SQLITE3_CLOSE（）SQLITE3_CREATE_COLLATION（）SQLITE3_COLLATION_NEEDED（）SQLITE3_CREATE_FUNCTION（）SQLITE3_PREPARE（）SQLITE3_EXEC（）SQLITE3_FINALIZE（）SQLITE3_GET_TABLE（）SQLITE3_OPEN（）SQ