C++通过OCCI操作Oracle数据库详解

　　今日趁空，尝试用C++操作Oracle数据库。大致步骤列举如下：

1.安装OCCI

如果oracle数据库默认没有安装OCCI，可以自己从官网上下载与自己数据库版本一致的API，地址：http://www.oracle.com/technetwork/topics/linuxsoft-082809.html  ； 其中包含四个软件包：

oracle-instantclient-sqlplus-10.2.0.5-1.i386.rpm

oracle-instantclient-devel-10.2.0.5-1.i386.rpm

oracle-instantclient-odbc-10.2.0.5-1.i386.rpm

oracle-instantclient-basic-10.2.0.5-1.i386.rpm

安装完成之后，会在/usr/lib下多个oracle 共享库文件夹，在/usr/include下多个oracle 头文件（接口）文件夹（可以将他们放到环境变量中）。我的数据库版本是10.2.0，下面以此为例。

2.编写HelloWorld程序测试连接

#include <iostream>

#define LINUXOCCI //避免函数重定义错误

#include <occi.h>

using namespace std;

using namespace oracle::occi;

int main()

{

   Environment *env=Environment::createEnvironment(Environment::DEFAULT);

   cout<<"success"<<endl;

   string name = "scott";

   string pass = "tiger";

   string srvName = "127.0.0.1:1522/orcl";

   try

   {

      Connection *conn = env->createConnection(name, pass);

      cout<<"conn success"<<endl;

      env->terminateConnection(conn);

   }

   catch(SQLException e)

   {

      cout<<e.what()<<endl;

       return -1;

   }

   Environment::terminateEnvironment(env);

   cout<<"end!"<<endl;

   return 0;
}

编译命令：

g++ test.cc -o test -I/usr/include/oracle/10.2.0.5/client -L/usr/lib/oracle/10.2.0.5/client/lib -locci -lsqlplus

我没有将occi的路径加入到环境变量中，所以此处要显示列出目录才能通过编译，找到共享库。

运行./test会报错，libocci.so找不到，解决办法很简单：将/usr/lib/oracle/.../lib下的库加入到LD_LIBRARY_PATH中就可以了。

输出结果：

success

conn success

end!

注：这件不幸的事情可能只发生在我身上了，本人系统中有三个用户，其中一个是oracle，而程序是用另一个用户写的，于是编译通过了，但是运行总是报错：

ORA-12162: TNS:net service name is incorrectly specified

后来查明，这个是由于没有设置并导出ORACLE_SID。换了oracle用户试试，居然运行通过了,真的很伤心，原来那个用户没有设置Oracle环境变脸怎么能直接本地访问呢。

3.进行一些操作，执行sql语句

Employees.h

/*

* A simple OCCI test application

* This file contains the Employees class declaration

*/

 

#include <iostream>

#include <occi.h>

#include <iomanip>

 

using namespace oracle::occi;

using namespace std;



class Employees {

public:

   Employees();

   virtual ~Employees();

 

   void List();



private:

   Environment *env;

   Connection  *con;



   string user;

   string passwd;

   string db;

 };

 

 Employees::Employees()

 {

   /*

 69    * connect to the test database as the HR

 70    * sample user and use the EZCONNECT method

 71    * of specifying the connect string. Be sure

 72    * to adjust for your environment! The format

 73    * of the string is host:port/service_name

 74 */

 

   user = "scott";

   passwd = "tiger";

  db = "127.0.0.1:1522/orcl";

 

   env = Environment::createEnvironment(Environment::DEFAULT);

 

   try

   {

     con = env->createConnection(user, passwd, db);

   }

   catch (SQLException& ex)

   {

     cout << ex.getMessage();

 

     exit(EXIT_FAILURE);

   }

}



 Employees::~Employees()

 {

   env->terminateConnection (con);



   Environment::terminateEnvironment (env);

 }

 

 void Employees::List()

{

  /*

104    * simple test method to select data from

105    * the employees table and display the results

106 */

 

   Statement *stmt = NULL;

   ResultSet *rs = NULL;

   string sql = "select EMPNO, ENAME, JOB " \

                "from EMP order by EMPNO";

 

   try

   {

     stmt = con->createStatement(sql);

   }

  catch (SQLException& ex)

  {

     cout << ex.getMessage();

   }

 

   if (stmt)

   {

     try

     {

      stmt->setPrefetchRowCount(32);



      rs = stmt->executeQuery();

    }

    catch (SQLException& ex)

     {

      cout << ex.getMessage();

    }

 

    if (rs)

    {

      cout << endl << setw(8) << left << "EMPNO"

            << setw(22) << left << "ENAME"

           << setw(27) << left << "JOB"

           << endl;

       cout << setw(8) << left << "======"

            << setw(22) << left << "===================="

            << setw(27) << left << "========================="

           << endl;

 

       while (rs->next()) {

        cout << setw(8) << left << rs->getInt(1)

            << setw(22) << left << (rs->isNull(2) ? "n/a" : rs->getString(2))

              << setw(27) << left << rs->getString(3)

              << endl;

      }



       cout << endl;

       stmt->closeResultSet(rs);

     }

     con->terminateStatement(stmt);

   }

 }

 

main.cc

 #include "Employees.h"



 using namespace std;

 using namespace oracle::occi;



 int main (void)

 {

   /*

 48    * create an instance of the Employees class,

 49    * invoke the List member, delete the instance,

 50    * and prompt to continue...

 51 */

 

   Employees *pEmployees = new Employees();

 

   pEmployees->List();



   delete pEmployees;

 

   cout << "ENTER to continue...";

 

   cin.get();

 

   return 0;

 }

 

运行结果就不说了，反正是oracle里自带的emp表。