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 from105    * the employees table and display the results106 */    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。