Linux下g++编译C++连接oracle（OCCI）出现的问题及解决方式_C/C++_编程开发_程序员俱乐部

  由于项目原因，开始学习C++，刚接触半个多月，今天参考网上例子，写了个简单的C++连接ORACLE的DEMO，可是使用g++编译时不顺利，不是报这个错就是那个，最后参考网上的解决方式和个人理解，终于调试好了，现把编译中出现的问题和解决方法总结出来。

  源代码
 

#include <iostream>
#include <string>
#include "occi.h"
using namespace oracle::occi;
using namespace std;

int main()
{
        string usr="sys";
        string pwd="orcl";
        string SID="ORCL";
        string date;

        Environment *env=Environment::createEnvironment(Environment::OBJECT);
        Connection *conn= env->createConnection(usr,pwd,SID);//all strings
        if(conn)
                cout<<"success createConnection!"<<endl;
        else
                cout<<"failure createConnection!"<<endl;

        Statement *stmt = conn->createStatement();
        string sSQL = "select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual";
        stmt->setSQL(sSQL);


        ResultSet *rs = stmt->executeQuery();
        if(rs->next())
        {
                date = rs->getString(1);
        }

        cout<<"now time :"<<date<<endl;

        env->terminateConnection(conn);
        Environment::terminateEnvironment(env);

        return 0;
}
  

  本人linux上安装oracle路径：/opt/app/oracle/product/10.2.0/db_1

  编译命令：g++ -o conn -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib conn_db.cpp -g

问题一：编译时报如下错误：
    

      [oracle@localhost demo]$ g++ g++ -o conn -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib -lclntsh -locci /usr/lib/libstdc++.so.5 conn_db.cpp -g
g++: g++: No such file or directory
conn_db.cpp:3:18: error: occi.h: No such file or directory
conn_db.cpp:4: error: 'oracle' has not been declared
conn_db.cpp:4: error: 'occi' is not a namespace-name
conn_db.cpp:4: error: expected namespace-name before ';' token
conn_db.cpp: In function 'int main()':
conn_db.cpp:14: error: 'Environment' was not declared in this scope
conn_db.cpp:14: error: 'env' was not declared in this scope
conn_db.cpp:14: error: 'Environment' is not a class or namespace
conn_db.cpp:14: error: 'Environment' is not a class or namespace
conn_db.cpp:15: error: 'Connection' was not declared in this scope
conn_db.cpp:15: error: 'conn' was not declared in this scope
conn_db.cpp:21: error: 'Statement' was not declared in this scope
conn_db.cpp:21: error: 'stmt' was not declared in this scope
conn_db.cpp:26: error: 'ResultSet' was not declared in this scope
conn_db.cpp:26: error: 'rs' was not declared in this scope
conn_db.cpp:35: error: 'Environment' is not a class or namespace
     

  
    解决：编译时没有引入OCCI头文件，如果没有，先下载对应的ORACLE client安装，比如我的是oracle10g,下载了oracle-instantclient-basic-10.2.0.4-1.i386.zip，解压到一个目录下(/home/oracle/oracle/include)，然后在编译文件的时候引进这个解压目录

   编译命令增加OCCI目录：g++ -o conn -I/home/oracle/oracle/include -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib conn_db.cpp -g


问题2：找不到对应函数
 

   [oracle@localhost demo]$ g++ -o conn -I/home/oracle/oracle/include -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib conn_db.cpp -Wall -O -g
/tmp/cclFs9xq.o: In function `main':
/home/oracle/oracle/demo/conn_db.cpp:14: undefined reference to `oracle::occi::Environment::createEnvironment(oracle::occi::Environment::Mode, void*, void* (*)(void*, unsigned int), void* (*)(void*, void*, unsigned int), void (*)(void*, void*))'
/home/oracle/oracle/demo/conn_db.cpp:35: undefined reference to `oracle::occi::Environment::terminateEnvironment(oracle::occi::Environment*)'
collect2: ld returned 1 exit status 
 

解决：增加libocci.so和libclntsh.so指定编译
 
  修改后的编译命令： g++ -o conn -I/home/oracle/oracle/include -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib conn_db.cpp -lclntsh -locci -Wall -O -g

  另外可能在引入-lclntsh -locci编译时可能会报找不到以下错误：
    

     [oracle@localhost demo]$ g++ -o conn -I/home/oracle/oracle/include -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib conn_db.cpp -lclntsh -locci /usr/lib/libstdc++.so.5 -Wall -O -g
/usr/bin/ld: cannot find -lclntsh
collect2: ld returned 1 exit status
[oracle@localhost demo]$ 
     

     解决：这是因为没有找到libclntsh.so和libocci.so链接库,你在可以把oracle client安装目录下把这两个文件拷贝到$ORACLE_HOME/lib目录下，或加到/usr/lib目录下就可以了

问题三：occi在linux编译运行时报libstdc++.so.6冲突的问题
   

[oracle@localhost demo]$ g++ -o conn -I/home/oracle/oracle/include -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib conn_db.cpp -lclntsh -locci -Wall -O -g
/usr/bin/ld: warning: libstdc++.so.5, needed by /opt/app/oracle/product/10.2.0/db_1/lib/libocci.so, may conflict with libstdc++.so.6

  解决：OCCI库在linux编译的时候，由于linux版本太高，会提示以上情况，实际上，在大多数linux系统上，还保留有libstdc++5的库，自己手工在编译的时候加上去就好了

  修改后的编译命令：g++ -o conn -I/home/oracle/oracle/include -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib -lclntsh -locci /usr/lib/libstdc++.so.5 conn_db.cpp -g

  编译通过后执行结果输出：
  

[oracle@localhost demo]$ g++ -o conn -I/home/oracle/oracle/include -L/opt/app/oracle/product/10.2.0/db_1/lib -L/opt/oracle/product/10.2.0/db_1/rdbms/lib conn_db.cpp -lclntsh -locci /usr/lib/libstdc++.so.5 -Wall -O -g
[oracle@localhost demo]$ ./conn
success createConnection!
now time :2010-11-14 22:49:24
[oracle@localhost demo]$