1 / 93

ORACLE C++ CALL INTERFACE(OCCI) Shankar Iyer, Oracle India.

ORACLE C++ CALL INTERFACE(OCCI) Shankar Iyer, Oracle India. OCCI – Today’s Agenda. Session I - Introduction - SQL/PLSQL Execution - Data classes Session II - Object Features - MetaData access. Session III - Scalability Features - 10i features Session IV - Interoperability with OCI

pboatwright
Download Presentation

ORACLE C++ CALL INTERFACE(OCCI) Shankar Iyer, Oracle India.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. ORACLE C++ CALL INTERFACE(OCCI) Shankar Iyer, Oracle India. Oracle C++ Call Interface(OCCI)

  2. OCCI – Today’s Agenda • Session I - Introduction - SQL/PLSQL Execution - Data classes Session II - Object Features - MetaData access • Session III - Scalability Features - 10i features Session IV - Interoperability with OCI - OCCI Performance Tuning - Demo application - Q & A Oracle C++ Call Interface(OCCI)

  3. OCCI – Introduction • C++ API to access Oracle database • Designed as small set of well encapsulated classes and interfaces for ease of use • Extensive features for relational access, object-relational access and scalability • Introduced in 9i, growing customer base Oracle C++ Call Interface(OCCI)

  4. OCCI - Benefits • Easy to learn and use, similar to JDBC in relational access • Based on Standard C++ and object oriented design • Higher productivity and quality in application development • Develop client-server, middle-tier and complex object modeling applications • Continuing enhancements by Oracle to add more features Oracle C++ Call Interface(OCCI)

  5. OCCI – Features • Complete SQL/PLSQL execution support • Scalability options to serve increasing number of users and requests • Seamless interface to manipulate objects of user-defined types as C++ class instances • Support for all Oracle data types and large object(LOB) types • Database metadata access Oracle C++ Call Interface(OCCI)

  6. OCCI – Building an application Application source files (use OCCI API and classes) OCCI API header files OTT generated C++ class headers C++ compiler OTT generated C++ class implementations OCCI header files • occi.h • occiCommon.h • occiControl.h • occiData.h • occiObjects.h OCCI library • libocci.so/libocci.a/oraocci9.dll OCCI library (static or dynamic) Linker Application Oracle C++ Call Interface(OCCI)

  7. OCCI – Application Initialization • A OCCI application is initialized by creating an Environment class instance • A Environment instance specifies :- • - Application modes : OBJECT/THREADED/MUTEXED etc • - object cache settings • - memory heap for OCCI classes • The Environment is the base for creating connections for further database access • To create an Environment, call createEnvironment static method of Environment class Oracle C++ Call Interface(OCCI)

  8. OCCI – Initialize Environment – Examples • Creating default Environment //include 1 header file for all OCCI classes/interfaces #include <occi.h> //create Environment Environment *env = Environment::createEnvironment(); //use the Environment instance to create connections, //database access … //terminate Environment by calling static method //Environment::terminateEnvironment Environment::terminateEnvironment(env); • Creating Environment for object access //create Environment – specify OBJECT mode Environment *env = Environment::createEnvironment(Environment::OBJECT); Oracle C++ Call Interface(OCCI)

  9. OCCI – Control classes Environment Create Create Create ConnectionPool Connection StatelessConnectionPool Get Get Get Create MetaData Statement Get Execute ResultSet Oracle C++ Call Interface(OCCI)

  10. OCCI – Connecting to database • A user connection is represented by a Connection class instance • Call the createConnection method of Environment class to create a connection • - Connection *Environment::createConnection( • const string &userName, const string &password, • const string &connectString) • Use the Connection object to access data, execute SQL commands, work with objects • End connection by calling Environment::terminateConnection • Advanced mechanisms like connection pooling, session pooling, proxy authentication also supported Oracle C++ Call Interface(OCCI)

  11. OCCI – Create Connection - Example //First need Environment Environment *env = Environment::createEnvironment(); Connection *conn=env->createConnection(“scott”,”tiger”,””); //3rd parameter is db name/TNS alias ..//database access – use the Connection object .. .. //logoff and terminate connection env->terminateConnection(conn); Oracle C++ Call Interface(OCCI)

  12. OCCI – Executing SQL/PLSQL • Execute DDL/DML statements, SELECT queries, PL/SQL blocks and retrieve results • Statement class for preparing & executing SQL/PLSQL statements, getting PL/SQL OUT results • ResultSet class for fetching SELECT query results • Uniform interface for binding and getting values of all data types - setXXX methods of Statement - getXXX methodsof Statement & ResultSet • Data type conversions automatically handled by OCCI Oracle C++ Call Interface(OCCI)

  13. OCCI – Executing SQL – Usage • Create a Statement object with Connection::createStatement() • Specify SQL command(DDL/DML/query) as argument to :- • Connection::createStatement(string &sql); • Statement::setSQL(string &sql); • Statement::execute(string &sql); - can be used for any SQL, returns status • Statement::executeUpdate(string &sql); - returns Insert/Update/Delete count • Statement::executeQuery(string &sql); - returns ResultSet • Use setXXX methods of Statement to pass input bind values • Execute the SQL statement using one of the execute methods of Statement • For SELECT queries, fetch the results using ResultSet class object Oracle C++ Call Interface(OCCI)

  14. OCCI – Executing SQL – Examples • Simple DML Insert //createStatement() on Connection class gives a Statement //instance Statement *stmt = conn->createStatement(“ insert into Dept(Deptno,Dname, Loc) values (1, ‘ACCOUNTS’, ‘ZONE1’ ”); //executeUpdate for all INSERT/UPDATE/DELETE stmt->executeUpdate(); conn->terminateStatement(stmt); • DML Insert with bind Statement *stmt = conn->createStatement(“ insert into Emp(EmpNo,Ename) values(:1, :2) ”); //1 and 2 are bind placeholders int empno = 2; string empname = “JOHN W”; //first parameter is bind position, second is value stmt->setInt(1, empno); stmt->setString(2, empname); stmt->executeUpdate(); Oracle C++ Call Interface(OCCI)

  15. OCCI – Executing SELECT – Examples • Executing Select queries and fetching results Statement *stmt = conn->createStatement(“ select Empno, Ename, Sal from Emp where Hiredate >= :1”); //automatically converted to Date stmt->setString(1, “01-JAN-1987”); //executeQuery returns a ResultSet ResultSet *rs = stmt->executeQuery(); //ResultSet::next fetches rows and returns FALSE //when no more rows while (rs->next() == true) { //get values using the getXXX methods of ResultSet empno = rs->getInt(1); empname = rs->getString(2); empsalary = rs->getFloat(3); } stmt->closeResultSet(rs);//to free resources Oracle C++ Call Interface(OCCI)

  16. OCCI – DML on multiple rows using Iterations • DML(INSERT/UPDATE/DELETE) of multiple rows in single roundtrip Statement *stmt = conn->createStatement(“insert into emp (empno, ename) values (:1, :2)”); //specify max iterations stmt->setMaxIterations(10);//number of rows //specify maximum data size for types like string stmt->setMaxParamSize(2, 100); //set values and add iterations stmt->setInt(1, 1001); stmt->setString(2, “JOHN”); stmt->addIteration(); stmt->setInt(1, 1002); stmt->setString(2, “JOE”); stmt->addIteration(); …//repeat iterations,do not call addIteration after last set stmt->executeUpdate();//will insert 10 rows in single trip Oracle C++ Call Interface(OCCI)

  17. OCCI – SQL Execution – Streaming • Bind/fetch data in pieces, typically used for LONG columns • Set binary/character streaming mode on Statement/ResultSet and use getStream() to get Stream • Use read/write methods of Stream Statement *stmt = conn->createStatement(“Select LongCol…”); ResultSet *rs = rs->executeQuery(); //indicate character streaming mode rs->setCharacterStreamMode(1, 100000);//col=1,maxsize=100000 while (rs->next()) { Stream *col = rs->getStream(1); char buffer[1024]; while (col->readBuffer(buffer, 1024) != -1) //process data } //similary use Stream::writeBuffer(),writeLastBuffer() Oracle C++ Call Interface(OCCI)

  18. OCCI – Executing PL/SQL • Create a Statement object and specify PL/SQL block to be executed • Pass any input arguments(IN and IN/OUT) to the PLSQL function/procedure/block by setXXX methods of Statement • Specify any OUT parameters by Statement::registerOutParam, sizes of OUT parameters by Statement::setMaxParamSize • Execute the PL/SQL block using Statement::execute() • Retrieve function result/OUT/IN OUT parameters by getXXX methods of Statement Oracle C++ Call Interface(OCCI)

  19. OCCI – PLSQL – Examples • Calling PL/SQL function/procedure //PLSQL function : function CalculateBonus(EmpNo IN Number, // EmpStatus IN OUT VARCHAR2, // Bonus OUT Number) RETURN VARCHAR2 //call function using anonymous block Statement *stmt = conn->createStatement(“ begin :1 := CalculateBonus( :2, :3, :4); end;”); //bind position 1 is the function’s return value stmt->setInt(2, 100); //IN parameter stmt->setString(3, “Active”); //IN OUT parameter //call registerOutParam for each OUT parameter stmt->registerOutParam(1, OCCISTRING, 1000);//function’s return value stmt->setMaxParamSize(1, 100);//setMaxParamSize for STRING types stmt->registerOutParam(4, OCCIFLOAT); stmt->execute(); //use getXXX methods of Statement to get OUT parameters, return value string msg = stmt->getString(1); //function return value string newstatus = stmt->getString(3);//IN OUT parameter float bonus = stmt->getFloat(4); //OUT parameter Oracle C++ Call Interface(OCCI)

  20. OCCI – SQL/PLSQL – Data buffer interface • To provide and receive data in user buffers for Statement and ResultSet • Bypasses OCCI and C++ specific datatypes like string/Date etc, minimizing data copies • Used in array inserts(any DML) and array fetches - array DML : Statement::executeArrayUpdate(int nrows) - array fetch : ResultSet::next(int nrows) • setXXX and getXXX methods should not be used if data buffer interface is used for a column Oracle C++ Call Interface(OCCI)

  21. OCCI – SQL/PLSQL – Array fetch example char enames[10][20];//10 elements of length 20 chars each ub2 elens[10];//to receive the length of each element Statement *stmt = conn->createStatement("Select Ename from EMP"); ResultSet *rs = stmt->executeQuery(); //ResultSet::setDataBuffer(colIndex,buffer,type,elemsize, //lengths,ind,rc) //OCCI_SQLT_STR for char buffer rs->setDataBuffer(1, enames, OCCI_SQLT_STR, 20, elens, NULL, NULL); rs->next(5); //will fetch 5 rows in enames //do not call rs->getString(1) Oracle C++ Call Interface(OCCI)

  22. OCCI – SQL/PLSQL – Array insert example int empnos[5]; empnos[0] = 801; empnos[1] = 802; stmt = conn->createStatement("insert into emp (empno) values (:1)"); //Statement::setDataBuffer(colIndex,buffer,type,elemsize, //lengths,ind,rc) //OCCIINT for int datatype stmt->setDataBuffer(1, empnos, OCCIINT, sizeof(int), NULL, NULL, NULL); stmt->executeArrayUpdate(2); //inserts 2 rows conn->commit(); Oracle C++ Call Interface(OCCI)

  23. OCCI – Error Handling • OCCI uses C++ exception mechanism to return all errors(in Oracle client/server or C++ STL) • Applications should have a try-catch block to handle exceptions • The exception object thrown is of SQLException class if error is in Oracle • SQLException is derived from standard C++ exception class • getErrorCode and getMessage methods of SQLException return Oracle error information Oracle C++ Call Interface(OCCI)

  24. OCCI – Error Handling – Example • Handling Oracle and C++ STL errors separately try { ResultSet *rs = stmt->executeQuery(); while (rs->next()) ………. } catch (SQLException &oraex) //Oracle/OCCI errors { int errno = oraex->getErrorCode();//returns the ORA number string errmsg = oraex->getMessage(); //more application error handling } catch (exception &ex) //any other C++/STL error { cout << “Error “ << ex.what() << endl; } Oracle C++ Call Interface(OCCI)

  25. OCCI – Data classes • Classes for using Oracle data types • Easy to use with comprehensive functionality • Used with Statement and ResultSet to insert/fetch values of these types Oracle C++ Call Interface(OCCI)

  26. OCCI – Data classes - Number // inserting a number Number bignum; bignum.fromText(env, “43613923333.233”, “99999999999999.999”); stmt->setNumber(1, bignum);//stmt is Statement // Create a Number from a double value double value = 2345.123; Number nu1 (value); // Some common Number methods Number abs = nu1.abs(); /* absolute value */ Number sin = nu1.sin(); /* sine */ // Cast operators can be used long lnum = (long) nu1; // Unary increment/decrement prefix/postfix notation nu1++; Oracle C++ Call Interface(OCCI)

  27. OCCI – Data classes – Date // inserting a Date // Create a Date object and bind it to the statement Date edate(env, 2000, 9, 3, 23, 30, 30); stmt->setDate(1, edate);//stmt is Statement // fetching and displaying a Date Date odate = rs->getDate(1); //rs is ResultSet Cout << odate.toText(“DD-MON-YYYY”, “GERMAN”); // interval between 2 dates IntervalDS diff; diff = odate.daysBetween(edate); Oracle C++ Call Interface(OCCI)

  28. OCCI – Large Object(LOB) support • Support for BLOB, CLOB/NCLOB and BFILE data types • Simple, consistent, object-oriented interface • OCCI classes :- Bfile, Clob, Blob • Used in relational insert/fetch(column of LOB type) or as object attributes :- • - Statement::setBfile(int column, Bfile &value); • - Statement::setClob(int column, Clob &value); • - Statement::setBlob(int column, Blob &value); • - Bfile Statement/ResultSet::getBfile(int column); • - Clob Statement/ResultSet::getClob(int column); • - Blob Statement/ResultSet::getBlob(int column); • Streamed read/write support Oracle C++ Call Interface(OCCI)

  29. OCCI – LOB support – Examples • Reading a BLOB Statement *stmt = conn->createStatement(“select resume from emp”); ResultSet *rs = stmt->executeQuery(); rs->next(); //fetch 1 row //Blob ResultSet::getBlob(int column) Blob resume = rs->getBlob(1); char buffer[100]; int bytesRead, offset = 1; while ((bytesRead = resume.read(100, buffer, 100, offset)) > 0) { //process data read //move offset to read next offset = offset + bytesRead; } Oracle C++ Call Interface(OCCI)

  30. OCCI – LOB support - Examples • Inserting/updating a CLOB Statement *stmt = conn->createStatement(“ insert into documents values (:1) ”); //create empty Clob Clob doccontents(conn); doccontents.setEmpty(); //1st insert will create LOB locator in database stmt->setClob(1, doccontents); stmt->executeUpdate(); conn->commit(); //now select the Clob again and add contents stmt = conn->createStatement(“select body from documents for update”); ResultSet *rs = stmt->executeQuery() doccontents = rs->getClob(1); doccontents.write (100, buffer, 100, 1); conn->commit(); Oracle C++ Call Interface(OCCI)

  31. OCCI – Objects • Access data from tables as C++ class instances • Automatic and intuitive mapping of object types to C++ class, no user code • Single data model for application and database • Develop complex and powerful object-oriented applications using Oracle’s object features, OCCI and C++ • Client-side cache for database transparency and performance Oracle C++ Call Interface(OCCI)

  32. OCCI – Objects – Oracle basics • Create object types to model application entities :- • create type employee as object ( empno number(5), name varchar2(30), hiredate date ); • Object types can be used to create object tables or as column types in relational table :- • create table emptab of employee; -- object table • create table person (name varchar2, age number, addr Address); -- column • Terminology :- • - Object : a row/item in a object table • - Reference : logical pointer/address of a object. • Every object in a object table has a reference Oracle C++ Call Interface(OCCI)

  33. OCCI – Objects – Oracle basics • REF datatype represents a reference to a object in a object table create type employee as object (… Dept REF Department, -- Reference to another object ); • Use REFs to model relationships (one-to-one or one-to-many) • - create type LineItem as object • (… • Item REF Product; -- reference to Product in Products table • ) • - create LineItems as varray(1000) of REF LineItem; -- collection type • create type PurchaseOrder as object • (… • ItemList LineItems; -- references to all LineItem’s of this order … • In a client application, references are used to fetch objects and navigate object relationships Oracle C++ Call Interface(OCCI)

  34. OCCI – Objects – Access methods • Navigational access :- • -no SQL • - Access database objects through references (REFs) • - create/modify/delete/fetch ‘persistent’ objects with normal C++ code • - complete transaction support • - objects are maintained in the client cache • Associative access :- • - use SQL • - create/fetch object values with Statement::setObject/Statement::getObject • and ResultSet::getObject • - no caching of objects since they are ‘values’ • Objects in a object table are accessed with navigational access. Columns of object types can be accessed with associative access Oracle C++ Call Interface(OCCI)

  35. OCCI – Object Type Translator(OTT) • Generates C++ class representations for Oracle object types • Application uses the C++ classes for creating & accessing persistent and transient objects • Object attributes are declared as member variables, with optional get/set access methods • Simple format input specification file • Generated code to be compiled & linked with the application Oracle C++ Call Interface(OCCI)

  36. OCCI – OTT – Data type mappings Oracle C++ Call Interface(OCCI)

  37. OCCI – OTT – Example generated class //Database type :- create type employee as object ( empno number(5), name varchar2(30), hiredate date ); //C++ class generated by OTT :- class EmployeeT : public oracle::occi::PObject { private: oracle::occi::Number EMPNO; string NAME; oracle::occi::Date HIREDATE; public: oracle::occi::Number getEmpno() const; void setEmpno(const oracle::occi::Number &value); string getName() const; void setName(const string &value); oracle::occi::Date getHiredate() const; void setHiredate(const oracle::occi::Date &value); Oracle C++ Call Interface(OCCI)

  38. OCCI – Using OTT #input type specification file (emp.typ) $ cat emp.typ TYPE employee As EmployeeT $ #Running OTT $ ott attraccess=private code=cpp cppfile=empo.cpp hfile=emph.h intype=emp.typ mapfile=empm.cpp userid=scott/tiger #generates emph.h, empo.cpp, empm.h, empm.cpp #OTT command-line options :- attraccess : attributes to be private(with get/set methods) or protected code : cpp for OCCI cppfile : name of C++ file for class implementations hfile : name of include file containing class declarations intype : input type specification file mapfile : name of C++ file containing the mapping register function userid : userid & password of the schema owning the object types Oracle C++ Call Interface(OCCI)

  39. OCCI – OTT – Example code fragments 1.//Database type :- create type employee as object ( Dept REF Department, -- Reference to another object ); //C++ class generated by OTT :- class EmployeeT : public oracle::occi::PObject { private: Ref< DepartmentT > DEPT; 2.//Database type :- create type employee as object ( Addr Address, -- embedded object ); //C++ class generated by OTT :- class EmployeeT : public oracle::occi::PObject { private: AddressT *ADDR; Oracle C++ Call Interface(OCCI)

  40. OCCI – OTT – Example code fragments 3.//Database type :- create type PhoneList as varray(10) of varchar2(30); create type customer as object ( PhoneNumbers PhoneList, -- attribute of collection type ); //C++ class generated by OTT :- class CustomerT : public oracle::occi::PObject { private: vector< string > PHONENUMBERS; 4.//Database type :- create type contractemployee under employee -- inheritance ( ); //C++ class generated by OTT :- class ContractEmployeeT : public EmployeeT { //C++ inheritance Oracle C++ Call Interface(OCCI)

  41. OCCI – Navigational Access • Retrieve objects and navigate relationships using references • A reference is represented in OCCI by Ref<T> class type, where T is the class generated by OTT for the object type • - Ref <AddressT> addrref; • Fetch initial REFs using SQL • - Statement *stmt = conn->createStatement(“Select Ref(a) from EmpTab a”); • ResultSet *rs = rs->executeQuery(); • rs->next(); • Ref<EmployeeT> empref = rs->getRef(1); • Access the object (‘pin’) using the C++ dereference operator • (->) on the Ref<T> variable • string empname = empref->getName(); • //the -> operator returns a object pointer to type T Oracle C++ Call Interface(OCCI)

  42. OCCI – Object cache • Client-side memory and fast lookup for objects • Maintains a fast lookup table between a reference and the corresponding C++ object • When a reference is dereferenced the first time, the cache fetches the object from the server, subsequent accesses get the object from the cache • Objects modified in the cache are updated in the database on transaction commit • When the cache exhausts memory, it frees up unused objects in a LRU style garbage collector Oracle C++ Call Interface(OCCI)

  43. OCCI – Pinning/unpinning of objects • A object is ‘pinned’ in the object cache when a reference (Ref<T>) to the object is dereferenced (-> operator) • The pin count of a object is incremented when additional Ref<T>’s point to the same object • Application can access/modify(get/set attributes) a object after it is dereferenced and pinned • A object is ‘unpinned’ and pin count decremented when the reference to it goes out of scope or points to a different object • When the pin count of a object is zero, it is eligible for garbage collection and will be freed when cache memory is full Oracle C++ Call Interface(OCCI)

  44. OCCI – Object cache – Example Ref<EmployeeT> empref = rs->getRef(1) //fetch and pin object string ename = empref->getName() Oracle Database //pass to another function by value //pin count increases by 1 PrintEmployee(empref); Client Object Cache 0 1 1 2 //pin count decreases by 1 on return function //navigate to address object Ref <AddressT> addrref = empref->getAddr(); string city = addrref->getCity(); //Modify street in address addrref->setStreet(“1, PARK AV”); addrref->markModify(); //process another Employee object //earlier object is unpinned empref = rs->getRef(1); Oracle C++ Call Interface(OCCI)

  45. OCCI – Modifying/Deleting objects – Example //fetch initial REF using SQL Statement *stmt = conn->createStatement(“Select Ref(a) From EmpTab a”); ResultSet *rs = stmt->executeQuery(); rs->next(); //fetch the Ref Ref<EmployeeT> empref = rs->getRef(1); //to modify a object, change attributes using set methods empref->setSalary(newsal);//pin and modify object //call markModified() method to indicate to OCCI/cache empref->markModified(); //Modified object will be written to database on commit conn->commit(); //to delete a object, call markDelete on Ref or pinned object empref.markDelete(); //or empref->markDelete(); Oracle C++ Call Interface(OCCI)

  46. OCCI – Creating new persistent objects • OTT generates a overloaded new operator in each class :- • void *operator new(size_t size, const oracle::occi::Connection * sess, • const string& table); • Use the new operator to create persistent objects in a database table :- • EmployeeT *newemp = new (conn, “SCOTT.EMPTAB”) EmployeeT() • Set attribute values of the new object • Object is saved in database when commit is done • New object will be managed by client cache after commit Oracle C++ Call Interface(OCCI)

  47. OCCI – Creating persistent object - Example Connection *conn = env->createConnection(“scott”,”tiger”); //EmployeeT class generated by OTT for type Employee //EMPTAB is object table of type Employee EmployeeT *newemp = new (conn, “SCOTT.EMPTAB”) EmployeeT(); newemp->setEmpno(1000); newemp->setEmpname(“JOHN W”); //use OCCI Date class Date hdate(env, 1, 1, 2003); newemp->setHiredate(hdate); //object will be saved in database on commit conn->commit(); //to get REF of object, use getRef() Ref <EmployeeT> = newemp->getRef(); Oracle C++ Call Interface(OCCI)

  48. OCCI – Objects – Associative Access • Use SQL to create and fetch object values • Can be used with object tables or with object type columns • - create type DepartmentT; • - create table DeptTab of DepartMentT; -- object table • - create table Region (…., Dept DepartmentT, …); -- object type column • Objects are not managed by cache since they are transient • Extensive support for collections • Easy way of using Oracle Object-Relational features Oracle C++ Call Interface(OCCI)

  49. OCCI – Associative Access – Examples • Insert into a object table Statement *stmt = conn->createStatement(“ insert into DeptTab values (:1) ”); DepartmentT *dept = new DepartmentT();//create transient instance //set values into dept members dept->setDeptNo(1); dept->setDeptName(“HR”); stmt->setObject(1, dept); stmt->executeUpdate(); • Insert into a table with object type column Statement *stmt = conn->createStatement(“ insert into Region(Area, Dept) values (:1, :2) ”); stmt->setString(1, “North”); DepartmentT *dept = new DepartmentT();//create transient instance //set values into dept members stmt->setObject(2, dept); stmt->executeUpdate(); Oracle C++ Call Interface(OCCI)

  50. OCCI – Associative Access – Examples • Selecting a object value Statement *stmt = conn->createStatement(“select value(a) from DeptTab a”); //or “select dept from Region” ResultSet *rs = stmt->executeQuery(); rs->next();//fetch DepartmentT *dept = rs->getObject(1); //access dept members cout << dept->getDeptNo() << endl; cout << dept->getDeptName() << endl; Oracle C++ Call Interface(OCCI)

More Related