外文原文ACCESSINGANDMANIPULATINGORACLEDATATHISCHAPTERDESCRIBESDATAACCESSINORACLESQLFORMATS,ASOPPOSEDTOSTANDARDJAVAFORMATSASDESCRIBEDINTHEPREVIOUSCHAPTER,THEORACLESQLFORMATSAREAKEYFACTOROFTHEORACLEJDBCEXTENSIONS,OFFERINGSIGNIFICANTADVANTAGESINEFFICIENCYANDPRECISIONINMANIPULATINGSQLDATAUSINGORACLESQLFORMATSINVOLVESCASTINGYOURRESULTSETSANDSTATEMENTSTOORACLERESULTSET,ORACLESTATEMENT,ORACLEPREPAREDSTATEMENT,ANDORACLECALLABLESTATEMENTOBJECTS,ASAPPROPRIATE,ANDUSINGTHEGETORACLEOBJECT,SETORACLEOBJECT,GETXXX,ANDSETXXXMETHODSOFTHESECLASSESWHEREXXXCORRESPONDSTOTHETYPESINTHEORACLESQLPACKAGETHISCHAPTERCOVERSTHEFOLLOWINGTOPICSDATACONVERSIONCONSIDERATIONSRESULTSETANDSTATEMENTEXTENSIONSCOMPARISONOFORACLEGETANDSETMETHODSTOSTANDARDJDBCUSINGRESULTSETMETADATAEXTENSIONSDATACONVERSIONCONSIDERATIONSWHENJDBCPROGRAMSRETRIEVESQLDATAINTOJAVA,YOUCANUSESTANDARDJAVATYPES,ORYOUCANUSETYPESOFTHEORACLESQLPACKAGETHECLASSESINTHISPACKAGESIMPLYWRAPTHERAWSQLDATASTANDARDTYPESVERSUSORACLETYPESINPROCESSINGSPEEDANDEFFORT,THEORACLESQLCLASSESPROVIDETHEMOSTEFFICIENTWAYOFREPRESENTINGSQLDATATHESECLASSESSTORETHEUSUALREPRESENTATIONSOFSQLDATAASBYTEARRAYSTHEYDONOTREFORMATTHEDATAORPERFORMANYCHARACTERSETCONVERSIONSASIDEFROMTHEUSUALNETWORKCONVERSIONSONITTHEDATAREMAINSINSQLFORMAT,ANDTHEREFORENOINFORMATIONISLOSTFORSQLPRIMITIVETYPESSUCHASNUMBER,ANDCHAR,THEORACLESQLCLASSESSIMPLYWRAPTHESQLDATAFORSQLSTRUCTUREDTYPESSUCHASOBJECTSANDARRAYS,THECLASSESPROVIDEADDITIONALINFORMATIONSUCHASCONVERSIONMETHODSANDSTRUCTUREDETAILSIFYOUAREMOVINGDATAWITHINTHEDATABASE,THENYOUWILLPROBABLYWANTTOKEEPYOURDATAINORACLESQLFORMATIFYOUAREDISPLAYINGTHEDATAORPERFORMINGCALCULATIONSONITINAJAVAAPPLICATIONRUNNINGOUTSIDETHEDATABASE,THENYOUWILLPROBABLYWANTTOMATERIALIZETHEDATAASINSTANCESOFSTANDARDTYPESSUCHASJAVASQLORJAVALANGTYPESSIMILARLY,IFYOUAREUSINGAPARSERTHATEXPECTSTHEDATATOBEINASTANDARDJAVAFORMAT,THENYOUMUSTUSEONEOFTHESTANDARDFORMATSINSTEADOFORACLESQLFORMATCONVERTINGSQLNULLDATAJAVAREPRESENTSASQLNULLDATUMBYTHEJAVAVALUENULLJAVADATATYPESFALLINTOTWOCATEGORIESPRIMITIVETYPESSUCHASBYTE,INT,FLOATANDOBJECTTYPESCLASSINSTANCESTHEPRIMITIVETYPESCANNOTREPRESENTNULLINSTEAD,THEYSTORETHENULLASTHEVALUEZEROASDEFINEDBYTHEJDBCSPECIFICATIONTHISCANLEADTOAMBIGUITYWHENYOUTRYTOINTERPRETYOURRESULTSINCONTRAST,JAVAOBJECTTYPESCANREPRESENTNULLTHEJAVALANGUAGEDEFINESANOBJECTWRAPPERTYPECORRESPONDINGTOEVERYPRIMITIVETYPEFOREXAMPLE,INTEGERFORINT,FLOATFORFLOATTHATCANREPRESENTNULLTHEOBJECTWRAPPERTYPESMUSTBEUSEDASTHETARGETSFORSQLDATATODETECTSQLNULLWITHOUTAMBIGUITYRESULTSETANDSTATEMENTEXTENSIONSTHEJDBCSTATEMENTOBJECTRETURNSANORACLERESULTSETOBJECT,TYPEDASAJAVASQLRESULTSETIFYOUWANTTOAPPLYONLYSTANDARDJDBCMETHODSTOTHEOBJECT,KEEPITASARESULTSETTYPEHOWEVER,IFYOUWANTTOUSETHEORACLEEXTENSIONSONTHEOBJECT,YOUMUSTCASTITTOANORACLERESULTSETTYPEALTHOUGHTHETYPEBYWHICHTHEJAVACOMPILERWILLIDENTIFYTHEOBJECTISCHANGED,THEOBJECTITSELFISUNCHANGEDFOREXAMPLE,ASSUMINGYOUHAVEASTANDARDSTATEMENTOBJECTSTMT,DOTHEFOLLOWINGIFYOUWANTTOUSEONLYSTANDARDJDBCRESULTSETMETHODSRESULTSETRSSTMTEXECUTEQUERY“SELECTFROMEMP“IFYOUNEEDTHEEXTENDEDFUNCTIONALITYPROVIDEDBYTHEORACLEEXTENSIONSTOJDBC,YOUCANSELECTTHERESULTSINTOASTANDARDRESULTSETOBJECT,ASABOVE,ANDTHENCASTTHATOBJECTINTOANORACLERESULTSETOBJECTLATERSIMILARLY,WHENYOUWANTTOEXECUTEASTOREDPROCEDUREUSINGACALLABLESTATEMENT,THEJDBCDRIVERSWILLRETURNANORACLECALLABLESTATEMENTOBJECTTYPEDASAJAVASQLCALLABLESTATEMENTIFYOUWANTTOAPPLYONLYSTANDARDJDBCMETHODSTOTHEOBJECT,THENKEEPITASACALLABLESTATEMENTTYPEHOWEVER,IFYOUWANTTOUSETHEORACLEEXTENSIONSONTHEOBJECT,YOUMUSTCASTITTOANORACLECALLABLESTATEMENTTYPEALTHOUGHTHETYPEBYWHICHTHEJAVACOMPILERWILLIDENTIFYTHEOBJECTISCHANGED,THEOBJECTITSELFISUNCHANGEDYOUUSETHESTANDARDJDBCJAVASQLCONNECTIONPREPARESTATEMENTMETHODTOCREATEAPREPAREDSTATEMENTOBJECTIFYOUWANTTOAPPLYONLYSTANDARDJDBCMETHODSTOTHEOBJECT,KEEPITASAPREPAREDSTATEMENTTYPEHOWEVER,IFYOUWANTTOUSETHEORACLEEXTENSIONSONTHEOBJECT,YOUMUSTCASTITTOANORACLEPREPAREDSTATEMENTTYPEWHILETHETYPEBYWHICHTHEJAVACOMPILERWILLIDENTIFYTHEOBJECTISCHANGED,THEOBJECTITSELFISUNCHANGEDKEYEXTENSIONSTOTHERESULTSETANDSTATEMENTCLASSESINCLUDEGETORACLEOBJECTANDSETORACLEOBJECTMETHODSTHATYOUCANUSETOACCESSANDMANIPULATEDATAINORACLESQLFORMATS,INSTEADOFSTANDARDJAVAFORMATSFORMOREINFORMATION,SEETHENEXTSECTION“COMPARISONOFORACLEGETANDSETMETHODSTOSTANDARDJDBC“COMPARISONOFORACLEGETANDSETMETHODSTOSTANDARDJDBCTHISSECTIONDESCRIBESGETANDSETMETHODS,PARTICULARLYTHEJDBCSTANDARDGETOBJECTANDSETOBJECTMETHODSANDTHEORACLESPECIFICGETORACLEOBJECTANDSETORACLEOBJECTMETHODS,ANDHOWTOACCESSDATAINORACLESQLFORMATCOMPAREDWITHJAVAFORMATALTHOUGHTHEREARESPECIFICGETXXXMETHODSFORALLTHEORACLESQLTYPESASDESCRIBEDIN“OTHERGETXXXMETHODS“ONPAGE77,YOUCANUSETHEGENERALGETMETHODSFORCONVENIENCEORSIMPLICITY,ORIFYOUARENOTCERTAININADVANCEWHATTYPEOFDATAYOUWILLRECEIVESTANDARDGETOBJECTMETHODTHESTANDARDJDBCGETOBJECTMETHODOFARESULTSETORCALLABLESTATEMENTRETURNSDATAINTOAJAVALANGOBJECTOBJECTTHEFORMATOFTHEDATARETURNEDISBASEDONITSORIGINALTYPE,ASFOLLOWSFORSQLDATATYPESTHATARENOTORACLESPECIFIC,GETOBJECTRETURNSTHEDEFAULTJAVATYPECORRESPONDINGTOTHECOLUMNSSQLTYPE,FOLLOWINGTHEMAPPINGSPECIFIEDINTHEJDBCSPECIFICATIONFORORACLESPECIFICDATATYPESSUCHASROWID,DISCUSSEDIN“ORACLEROWIDTYPE“ONPAGE633,GETOBJECTRETURNSANOBJECTOFTHEAPPROPRIATEORACLESQLCLASSSUCHASORACLESQLROWIDFORORACLEOBJECTS,GETOBJECTRETURNSANOBJECTOFTHEJAVACLASSSPECIFIEDINYOURTYPEMAPTYPEMAPSSPECIFYTHECORRELATIONBETWEENJAVACLASSESANDDATABASESQLTYPESANDAREDISCUSSEDIN“UNDERSTANDINGTYPEMAPSFORSQLDATAIMPLEMENTATIONS“ONPAGE911THEGETOBJECTPARAMETER_INDEXMETHODUSESTHECONNECTIONSDEFAULTTYPEMAPTHEGETOBJECTPARAMETER_INDEX,MAPENABLESYOUTOPASSINATYPEMAPIFTHETYPEMAPDOESNOTPROVIDEAMAPPINGFORAPARTICULARORACLEOBJECT,THENGETOBJECTRETURNSANORACLESQLSTRUCTOBJECTFORMOREINFORMATIONONGETOBJECTRETURNTYPES,SEETABLE71,“SUMMARYOFGETOBJECTANDGETORACLEOBJECTRETURNTYPES“ONPAGE76ORACLEGETORACLEOBJECTMETHODIFYOUWANTTORETRIEVEDATAFROMARESULTSETORCALLABLESTATEMENTINTOANORACLESQLOBJECT,THENCASTYOURRESULTSETTOANORACLERESULTSETTYPEORYOURCALLABLESTATEMENTTOANORACLECALLABLESTATEMENTTYPE,ANDUSETHEGETORACLEOBJECTMETHODWHENYOUUSEGETORACLEOBJECT,THEDATAWILLBEOFTHEAPPROPRIATEORACLESQLTYPEANDISRETURNEDINTOANORACLESQLDATUMOBJECTTHEORACLESQLTYPECLASSESEXTENDDATUMTHESIGNATUREFORTHEMETHODISPUBLICORACLESQLDATUMGETORACLEOBJECTINTPARAMETER_INDEXWHENYOUHAVERETRIEVEDDATAINTOADATUMOBJECT,YOUCANUSETHESTANDARDJAVAINSTANCEOFOPERATORTODETERMINEWHICHORACLESQLTYPEITREALLYISFORMOREINFORMATIONONGETORACLEOBJECTRETURNTYPES,SEETABLE71,“SUMMARYOFGETOBJECTANDGETORACLEOBJECTRETURNTYPES“ONPAGE76EXAMPLEUSINGGETORACLEOBJECTWITHARESULTSETTHEFOLLOWINGEXAMPLECREATESATABLETHATCONTAINSACOLUMNOFCHARACTERDATAINTHISCASE,AROWNUMBERANDACOLUMNCONTAININGABFILELOCATORASELECTSTATEMENTRETRIEVESTHECONTENTSOFTHETABLEINTOARESULTSETTHEGETORACLEOBJECTTHENRETRIEVESTHECHARDATAINTOTHECHAR_DATUMVARIABLEANDTHEBFILELOCATORINTOTHEBFILE_DATUMVARIABLENOTETHATBECAUSEGETORACLEOBJECTRETURNSADATUMOBJECT,THERESULTSMUSTBECASTTOCHARANDBFILE,RESPECTIVELYSTMTEXECUTE“CREATETABLEBFILE_TABLEXVARCHAR230,BBFILE“STMTEXECUTE“INSERTINTOBFILE_TABLEVALUESONE,BFILENAMETEST_DIR,FILE1“RESULTSETRSETSTMTEXECUTEQUERY“SELECTFROMBFILE_TABLE“WHILERSETNEXTCHARCHAR_DATUMCHARORACLERESULTSETRSETGETORACLEOBJECT1BFILEBFILE_DATUMBFILEORACLERESULTSETRSETGETORACLEOBJECT2EXAMPLEUSINGGETORACLEOBJECTINACALLABLESTATEMENTTHEFOLLOWINGEXAMPLEPREPARESACALLTOTHEPROCEDUREMYGETDATE,WHICHASSOCIATESACHARACTERSTRINGINTHISCASEANAMEWITHADATETHEPROGRAMPASSESTHESTRINGSCOTTTOTHEPREPAREDCALLANDREGISTERSTHEDATETYPEASANOUTPUTPARAMETERAFTERTHECALLISEXECUTED,GETORACLEOBJECTRETRIEVESTHEDATEASSOCIATEDWITHTHENAMESCOTTNOTETHATBECAUSEGETORACLEOBJECTRETURNSADATUMOBJECT,THERESULTSARECASTTOADATEOBJECTORACLECALLABLESTATEMENTCSTMTORACLECALLABLESTATEMENTCONNPREPARECALL“BEGINMYGETDATE,END“CSTMTSETSTRING1,“SCOTT“CSTMTREGISTEROUTPARAMETER2,TYPESDATECSTMTEXECUTEDATEDATEDATEORACLECALLABLESTATEMENTCSTMTGETORACLEOBJECT2SUMMARYOFGETOBJECTANDGETORACLEOBJECTRETURNTYPESTABLE71SUMMARIZESTHEINFORMATIONINTHEPRECEDINGSECTIONS,“STANDARDGETOBJECTMETHOD“AND“ORACLEGETORACLEOBJECTMETHOD“ONPAGE74THISTABLELISTSTHEUNDERLYINGRETURNTYPESFOREACHMETHODFOREACHORACLESQLTYPE,BUTKEEPINMINDTHESIGNATURESOFTHEMETHODSWHENYOUWRITEYOURCODEGETOBJECTALWAYSRETURNSDATAINTOAJAVALANGOBJECTINSTANCEGETORACLEOBJECTALWAYSRETURNSDATAINTOANORACLESQLDATUMINSTANCEYOUMUSTCASTTHERETURNEDOBJECTTOUSEANYSPECIALFUNCTIONALITYSEE“CASTINGYOURGETMETHODRETURNVALUES“ONPAGE710TABLE71SUMMARYOFGETOBJECTANDGETORACLEOBJECTRETURNTYPESFORINFORMATIONONTYPECOMPATIBILITYBETWEENALLSQLANDJAVATYPES,SEETABLE201,“VALIDSQLDATATYPEJAVACLASSMAPPINGS“ONPAGE202OTHERGETXXXMETHODSSTANDARDJDBCPROVIDESAGETXXXFOREACHSTANDARDJAVATYPE,SUCHASGETBYTE,GETINT,GETFLOAT,ANDSOONEACHOFTHESERETURNSEXACTLYWHATTHEMETHODNAMEIMPLIESABYTE,ANINT,AFLOAT,ANDSOONINADDITION,THEORACLERESULTSETANDORACLECALLABLESTATEMENTCLASSESPROVIDEAFULLCOMPLEMENTOFGETXXXMETHODSCORRESPONDINGTOALLTHEORACLESQLTYPESEACHGETXXXMETHODRETURNSANORACLESQLXXXOBJECTFOREXAMPLE,GETROWIDRETURNSANORACLESQLROWIDOBJECTSOMEOFTHESEEXTENSIONSARETAKENFROMTHEJDBC20SPECIFICATIONTHEYRETURNOBJECTSOFTYPEJAVASQLORORACLEJDBC2UNDERJDK11X,INSTEADOFORACLESQLFOREXAMPLE,COMPARETHEFOLLOWINGMETHODNAMESANDRETURNTYPESJAVASQLBLOBGETBLOBINTPARAMETER_INDEXORACLESQLBLOBGETBLOBINTPARAMETER_INDEXALTHOUGHTHEREISNOPARTICULARPERFORMANCEADVANTAGEINUSINGTHESPECIFICGETXXXMETHODS,THEYCANSAVEYOUTHETROUBLEOFCASTING,BECAUSETHEYRETURNSPECIFICOBJECTTYPESRETURNTYPESANDINPUTPARAMETERTYPESOFGETXXXMETHODSTABLE72SUMMARIZESTHEUNDERLYINGRETURNTYPESANDTHEINPUTPARAMETERTYPESFOREACHGETXXXMETHOD,ANDNOTESWHICHAREORACLEEXTENSIONSUNDERJDK12XANDJDK11XYOUMUSTCASTTOANORACLERESULTSETORORACLECALLABLESTATEMENTTOUSEMETHODSTHATAREORACLEEXTENSIONSTABLE72SUMMARYOFGETXXXRETURNTYPESTABLE72SUMMARYOFGETXXXRETURNTYPESCONTSPECIALNOTESABOUTGETXXXMETHODSTHISSECTIONPROVIDESADDITIONALDETAILSABOUTSOMEOFTHEGETXXXMETHODSGETBIGDECIMALNOTEJDBC20SUPPORTSASIMPLIFIEDMETHODSIGNATUREFORTHEGETBIGDECIMALMETHODTHEPREVIOUSINPUTSIGNATUREWASINTCOLUMNINDEX,INTSCALEORSTRINGCOLUMNNAME,INTSCALETHENEWINPUTSIGNATUREISSIMPLYINTCOLUMNINDEXORSTRINGCOLUMNNAMETHESCALEPARAMETER,USEDTOSPECIFYTHENUMBEROFDIGITSTOTHERIGHTOFTHEDECIMAL,ISNOLONGERNECESSARYTHEORACLEJDBCDRIVERSRETRIEVENUMERICVALUESWITHFULLPRECISIONGETDATE,GETTIME,ANDGETTIMESTAMPNOTEINJDBC20,THEGETDATE,GETTIME,ANDGETTIMESTAMPMETHODSHAVETHEFOLLOWINGINPUTSIGNATURESINTCOLUMNINDEX,CALENDARCALORSTRINGCOLUMNNAME,CALENDARCALTHEORACLEJDBCDRIVERSIGNORETHECALENDAROBJECTINPUT,BECAUSEITISNOTCURRENTLYFEASIBLETOSUPPORTJAVASQLDATETIMEZONEINFORMATIONTOGETHERWITHTHEDATAYOUSHOULDCONTINUETOUSEPREVIOUSINPUTSIGNATURESTHATTAKEONLYTHECOLUMNINDEXORCOLUMNNAMECALENDARINPUTWILLBESUPPORTEDINAFUTUREORACLEJDBCRELEASECASTINGYOURGETMETHODRETURNVALUESASDESCRIBEDIN“STANDARDGETOBJECTMETHOD“ONPAGE74,ORACLESIMPLEMENTATIONOFGETOBJECTALWAYSRETURNSAJAVALANGOBJECTINSTANCE,ANDGETORACLEOBJECTALWAYSRETURNSANORACLESQLDATUMINSTANCEUSUALLY,YOUWOULDCASTTHERETURNEDOBJECTTOTHEAPPROPRIATECLASSSOTHATYOUCOULDUSEPARTICULARMETHODSANDFUNCTIONALITYOFTHATCLASSINADDITION,YOUHAVETHEOPTIONOFUSINGASPECIFICGETXXXMETHODINSTEADOFTHEGENERICGETOBJECTORGETORACLEOBJECTMETHODSTHEGETXXXMETHODSENABLEYOUTOAVOIDCASTING,BECAUSETHERETURNTYPEOFGETXXXCORRESPONDSTOTHETYPEOFOBJECTRETURNEDFOREXAMPLE,GETCLOBRETURNSANORACLESQLCLOBINSTANCE,ASOPPOSEDTOAJAVALANGOBJECTINSTANCEEXAMPLECASTINGRETURNVALUESTHISEXAMPLEASSUMESTHATYOUHAVEFETCHEDDATAOFTYPECHARINTOARESULTSETWHEREITISINCOLUMN1BECAUSEYOUWANTTOMANIPULATETHECHARDATAWITHOUTLOSINGPRECISION,CASTYOURRESULTSETTOANORACLERESULTSET,ANDUSEGETORACLEOBJECTTORETURNTHECHARDATAINORACLESQLFORMATIFYOUDONOTCASTYOURRESULTSET,YOUHAVETOUSEGETOBJECT,WHICHRETURNSYOURCHARACTERDATAINTOAJAVASTRINGANDLOSESSOMEOFTHEPRECISIONOFYOURSQLDATATHEGETORACLEOBJECTMETHODRETURNSANORACLESQLCHAROBJECTINTOANORACLESQLDATUMRETURNVARIABLEUNLESSYOUCASTTHEOUTPUTCASTTHEGETORACLEOBJECTOUTPUTTOORACLESQLCHARIFYOUWANTTOUSEACHARRETURNVARIABLEANDANYOFTHESPECIALFUNCTIONALITYOFTHATCLASSSUCHASTHEGETCHARACTERSETMETHODTHATRETURNSTHECHARACTERSETUSEDTOREPRESENTTHECHARACTERSCHARCHARCHARORSGETORACLEOBJECT1CHARACTERSETCSCHARGETCHARACTERSETALTERNATIVELY,YOUCANRETURNTHEOBJECTINTOAGENERICORACLESQLDATUMRETURNVARIABLEANDCASTITLATERWHENYOUMUSTUSETHECHARGETCHARACTERSETMETHODDATUMRAWDATUMORSGETORACLEOBJECT1CHARACTERSETCSCHARRAWDATUMGETCHARACTERSETTHISUSESTHEGETCHARACTERSETMETHODOFORACLESQLCHARTHEGETCHARACTERSETMETHODISNOTDEFINEDONORACLESQLDATUMANDWOULDNOTBEREACHABLEWITHOUTTHECASTSTANDARDSETOBJECTANDORACLESETORACLEOBJECTMETHODSJUSTASTHEREISASTANDARDGETOBJECTANDORACLESPECIFICGETORACLEOBJECTINRESULTSETSANDCALLABLESTATEMENTSFORRETRIEVINGDATA,THEREISALSOASTANDARDSETOBJECTANDANORACLESPECIFICSETORACLEOBJECTINORACLEPREPAREDSTATEMENTSANDCALLABLESTATEMENTSFORUPDATINGDATATHESETORACLEOBJECTMETHODSTAKEORACLESQLINPUTPARAMETERSTOBINDSTANDARDJAVATYPESTOAPREPAREDSTATEMENTORCALLABLESTATEMENT,USETHESETOBJECTMETHOD,WHICHTAKESAJAVALANGOBJECTASINPUTTHESETOBJECTMETHODDOESSUPPORTAFEWOFTHEORACLESQLTYPESITHASBEENIMPLEMENTEDSOTHATYOUCANALSOINPUTINSTANCESOFTHEORACLESQLCLASSESTHATCORRESPONDTOJDBC20COMPLIANTORACLEEXTENSIONSBLOB,CLOB,BFILE,STRUCT,REF,ANDARRAYTOBINDORACLESQLTYPESTOAPREPAREDSTATEMENTORCALLABLESTATEMENT,USETHESETORACLEOBJECTMETHOD,WHICHTAKESANORACLESQLDATUMORANYSUBCLASSASINPUTTOUSESETORACLEOBJECT,YOUMUSTCASTYOURPREPAREDSTATEMENTORCALLABLESTATEMENTTOANORACLEPREPAREDSTATEMENTORORACLECALLABLESTATEMENTOBJECTEXAMPLEUSINGSETOBJECTANDSETORACLEOBJECTINAPREPAREDSTATEMENTTHISEXAMPLEASSUMESTHATYOUHAVEFETCHEDCHARACTERDATAINTOASTANDARDRESULTSETWHEREITISINCOLUMN1,ANDYOUWANTTOCASTTHERESULTSTOANORACLERESULTSETSOTHATYOUCANUSEORACLESPECIFICFORMATSANDMETHODSBECAUSEYOUWANTTOUSETHEDATAASORACLESQLCHARFORMAT,CASTTHERESULTSOFTHEGETORACLEOBJECTWHICHRETURNSTYPEORACLESQLDATUMTOCHARSIMILARLY,BECAUSEYOUWANTTOMANIPULATETHEDATAINCOLUMN2ASSTRINGS,CASTTHEDATATOAJAVASTRINGTYPEBECAUSEGETOBJECTRETURNSDATAOFTYPEOBJECTINTHISEXAMPLE,RSREPRESENTSTHERESULTSET,CHARVALREPRESENTSTHEDATAFROMCOLUMN1INORACLESQLCHARFORMAT,ANDSTRVALREPRESENTSTHEDATAFROMCOLUMN2INJAVASTRINGFORMATCHARCHARVALCHARORACLERESULTSETRSGETORACLEOBJECT1STRINGSTRVALSTRINGRSGETOBJECT2FORAPREPAREDSTATEMENTOBJECTPS,THESETORACLEOBJECTMETHODBINDSTHEORACLESQLCHARDATAREPRESENTEDBYTHECHARVALVARIABLETOTHEPREPAREDSTATEMENTTOBINDTHEORACLESQLDATA,THEPREPAREDSTATEMENTMUSTBECASTTOANORACLEPREPAREDSTATEMENTSIMILARLY,THESETOBJECTMETHODBINDSTHEJAVASTRINGDATAREPRESENTEDBYTHEVARIABLESTRVALPREPAREDSTATEMENTPSCONNPREPARESTATEMENT“TEXT_OF_PREPARED_STATEMENT“ORACLEPREPAREDSTATEMENTPSSETORACLEOBJECT1,CHARVALPSSETOBJECT2,STRVALOTHERSETXXXMETHODSASWITHGETXXXMETHODS,THEREARESEVERALSPECIFICSETXXXMETHODSSTANDARDSETXXXMETHODSAREPROVIDEDFORBINDINGSTANDARDJAVATYPES,ANDORACLESPECIFICSETXXXMETHODSAREPROVIDEDFORBINDINGORACLESPECIFICTYPESNOTEUNDERJDK11X,FORCOMPATIBILITYWITHTHEJDBC20STANDARD,ORACLEPREPAREDSTATEMENTANDORACLECALLABLESTATEMENTCLASSESPROVIDESETXXXMETHODSTHATTAKEORACLEJDBC2INPUTPARAMETERSFORBLOBS,CLOBS,OBJECTREFERENCES,ANDARRAYSFOREXAMPLE,ASETBLOBMETHODTAKESANORACLEJDBC2BLOBINPUTPARAMETER,WHEREITWOULDTAKEAJAVASQLBLOBINPUTPARAMETERUNDERJDK12XSIMILARLY,THEREARETWOFORMSOFTHESETNULLMETHODVOIDSETNULLINTPARAMETERINDEX,INTSQLTYPEVOIDSETNULLINTPARAMETERINDEX,INTSQLTYPE,STRINGSQL_TYPE_NAME中文翻譯存取訪問和操作ORACLE數(shù)據(jù)這一章描述數(shù)據(jù)存取訪問以O(shè)RACLESQL方式，和標(biāo)準(zhǔn)JAVA形式相對照。因?yàn)樵谝郧暗恼鹿?jié)描述過，ORACLESQL方式是ORACLEJDBC的一個(gè)重要擴(kuò)展因素，它在操作SQL數(shù)據(jù)時(shí)在效率和精確度上有著重要的優(yōu)勢。用ORACLESQL方式涉及到計(jì)算結(jié)果集和語句相關(guān)ORACLERESULTSET，ORACLESTATEMENT，ORACLEPREPAREDSTATEMENT，和ORACLECALLABLESTATEMENT對象，按照適合的，用這些類的GETORACLEOBJECT，SETORACLEOBJECT，GETXXX和SETXXX方法XXX是在ORACLESQL包里相符的類型。這一章包括以下標(biāo)題數(shù)據(jù)轉(zhuǎn)換考慮結(jié)果集和語句擴(kuò)展關(guān)于標(biāo)準(zhǔn)JDBC，ORACLE的GET和SET方法的比較用結(jié)果集原數(shù)據(jù)擴(kuò)展數(shù)據(jù)轉(zhuǎn)換考慮當(dāng)JDBC程序檢索SQL數(shù)據(jù)到JAVA，你可以用標(biāo)準(zhǔn)JAVA類型或者ORACLESQL包中的類型。在此包中的類簡單地包裝原SQL數(shù)據(jù)。標(biāo)準(zhǔn)類型與ORACLE類型在過程的速度和影響中，ORACLESQL類提供了最有效率的方法表現(xiàn)數(shù)據(jù)。這些類按照BYTE排列形式存儲常見的SQL數(shù)據(jù)表現(xiàn)形式。這些類以比特存儲常見的SQL數(shù)據(jù)形式。它們不重新格式化或執(zhí)行任何字符組轉(zhuǎn)換除了常見的網(wǎng)絡(luò)轉(zhuǎn)換。數(shù)據(jù)保留SQL形式，因此沒有信息丟失。對于SQL的標(biāo)準(zhǔn)類型如NUMBER，和CHAR，ORACLESQL類簡單地包裝了SQL數(shù)據(jù)。對于結(jié)構(gòu)類型如OBJECTS和數(shù)組，這些類提供傳統(tǒng)的信息如轉(zhuǎn)化方法和結(jié)構(gòu)細(xì)節(jié)。如果你在數(shù)據(jù)庫里移動數(shù)據(jù)，你可能會想要保持?jǐn)?shù)據(jù)以O(shè)RACLESQL的形式。如果你要運(yùn)行在數(shù)據(jù)庫外的JAVA程序中顯示數(shù)據(jù)或執(zhí)行計(jì)算，你可能想實(shí)現(xiàn)數(shù)據(jù)以實(shí)例標(biāo)準(zhǔn)類型像JAVASQL或者JAVALANG型。相似地，如果你想要分析數(shù)據(jù)成為一個(gè)標(biāo)準(zhǔn)JAVA形式，你必須用一個(gè)標(biāo)準(zhǔn)形式代替ORACLESQL。轉(zhuǎn)換SQL空數(shù)據(jù)JAVA是以JAVA值空來表示一個(gè)SQL空值。JAVA數(shù)據(jù)類型分為兩種標(biāo)準(zhǔn)類型如BYTE，INT，F(xiàn)LOAT和對象類型類事例。標(biāo)準(zhǔn)類型不能表示NULL。但是可以存儲NULL用零表示JDBC定義。這樣當(dāng)你顯示你的結(jié)果時(shí)不會含糊不清。相反地，JAVA對象類型能夠表現(xiàn)空值。JAVA語言定義一個(gè)對象封裝類型相對應(yīng)每一個(gè)能表示空值的標(biāo)準(zhǔn)類型例如，INTEGER對應(yīng)INT，F(xiàn)LOAT對應(yīng)FLOAT。對象封裝類型必須用作SQL數(shù)據(jù)目標(biāo)去檢測SQL控制避免含糊不清。結(jié)果集和語句擴(kuò)展JDBC語句對象返回一個(gè)ORACLERESULTSET對象，定義為一個(gè)JAVASQLRESULTSET，如果你只想標(biāo)準(zhǔn)JDBC方法適用于對象，應(yīng)該把它設(shè)為RESULTSET類型。然而你想用ORACLE擴(kuò)展對象，你必須把它設(shè)置為ORACLERESULTSET類型。盡管通過JAVA編譯器能指定對象的這種類型可以改變，但對象自身不能夠改變。舉個(gè)例子，假設(shè)你定義了一個(gè)標(biāo)準(zhǔn)語句對象STMT，只想用標(biāo)準(zhǔn)JDBCRESULTSET方法，執(zhí)行下面的語句RESULTSETRSSTMTEXECUTEQUERY“SELECTFROMEMP”如果你需要ORACLE可擴(kuò)展的函數(shù)性到JDBC，可以選擇結(jié)果變成一個(gè)標(biāo)準(zhǔn)的結(jié)果集對象，而且之后可以把對象變成一個(gè)ORACLERESULTSET對象。相似地當(dāng)想要通過一個(gè)可執(zhí)行語句執(zhí)行一個(gè)存儲過程，JDBC驅(qū)動程序?qū)⒎祷匾粋€(gè)通過一個(gè)JAVASQLCALLABLESTATEMENT定義的ORACLECALLABLESTATEMENT對象。如果你只想標(biāo)準(zhǔn)JDBC方法適用于對象，應(yīng)該把它設(shè)為一個(gè)CALLABLESTATEMENT類型。然而你想用ORACLE擴(kuò)展對象，你必須把它設(shè)置為ORACLECALLABLESTATEMENT類型。盡管通過JAVA編譯器能指定對象的這種類型可以改變，但對象自身不能夠改變。用一個(gè)標(biāo)準(zhǔn)JDBCJAVASQLCONNECTIONPREPARESTEMENT方法去創(chuàng)建一個(gè)PREPARESTEMENT對象。如果你只想標(biāo)準(zhǔn)JDBC方法適用于對象，應(yīng)該把它設(shè)為一個(gè)PREPARESTEMENT類型。然而你想用ORACLE擴(kuò)展對象，你必須把它設(shè)置為ORACLEPREPARESTEMENT類型。盡管通過JAVA編譯器能指定對象的這種類型可以改變，但對象自身不能夠改變。結(jié)果集和語句類擴(kuò)展的關(guān)鍵包括GETORACLEOBJECT和SETORACLEOBJECT方法，它們能夠使用和操作數(shù)據(jù)以O(shè)RACLESQL的方式代替標(biāo)準(zhǔn)JAVA方式。更多的信息，請看下一章”連接標(biāo)準(zhǔn)JDBCORACLE的GET、SET方法比較”。連接標(biāo)準(zhǔn)JDBCORACLE的GET、SET方法比較這一章描述GET和SET方法，特別是JDBC標(biāo)準(zhǔn)GETOBJECT、SETOBJECT方法和ORACLESPECIFICGETORACLEOBJECT和SETORACLEOBJECT方法，以及怎樣存取訪問數(shù)據(jù)以和JAVA方式比較的ORACLESQL方式。盡管有特有的GET方法給所有的ORACLESQL類型其它的GET方法描述在77頁，但用常規(guī)的GET方法就很方便和簡單，或者你不確定收到哪種數(shù)據(jù)類型更提前。標(biāo)準(zhǔn)GETOBJECT方法一個(gè)結(jié)果集或者可執(zhí)行語句的標(biāo)準(zhǔn)JDBCGETOBJECT方法以一個(gè)JAVALANGOBJECT對象返回?cái)?shù)據(jù)。數(shù)據(jù)返回的方法基于它的原類型，如下SQL數(shù)據(jù)類型不是數(shù)據(jù)庫特有的，GETOBJECT方法返回符合列表SQL類型的缺省JAVA類型，遵循JDBC具體指定的映像。ORACLESPECIFIC數(shù)據(jù)類型例如ROWID，討論ORACLEROWID類型在633頁，GETOBJECT返回一個(gè)合適ORACLESQL類的對象例如ORACLESQLROWIDORACLE對象，GETOBJECT返回一個(gè)類型映像規(guī)定的JAVA類對象。類型映像具體定義了JAVA類和數(shù)據(jù)庫SQL之間的相互關(guān)系，討論”理解類型映像SQL數(shù)據(jù)執(zhí)行”在911頁。GETOBJECTPARAMETER_INDEX方法用缺省類型映射聯(lián)系。GETOBJECTPARAMETER_INDEX，MAP方法能以一個(gè)類型映射通過。如果類型映射不能提供一個(gè)對特殊ORACLE對象的映射，GETOBJECT返回一個(gè)ORACLESQLSTUCT對象。更多GETOBJECT信息，返回類型，見表71，”GETOBJECT、GETORACLEOBJECT和返回類型的概述”在76頁。ORACLEGETORACLEOBJECT方法如果想要從一個(gè)結(jié)果集和可執(zhí)行語句中檢索數(shù)據(jù)使之變成ORACLESQL對象，那么就把結(jié)果集變成一個(gè)ORACLERESULTSET類型或者把可執(zhí)行語句變成一個(gè)ORACLECALLABLESTATEMENT類型，用GETORACLEOBJECT方法。當(dāng)你用GETORACLEOBJECT方法，數(shù)據(jù)將會是一個(gè)合適的ORACLESQL類型，以O(shè)RACLESQLDATUM對象返回ORACLESQL類型繼承DATUM。方法標(biāo)記是PUBLICORACLESQLDATUMGETORACLEOBJECTINTPARAMETER_INDEX當(dāng)時(shí)數(shù)據(jù)恢復(fù)成一個(gè)DATUM對