《C语言连接ORACLE数据库》源码例程

简述：
用C语言连接ORACLE数据库。
有两个思路和目的

思路一）
本地环境：UBUNTU 7.04,ORACLE 10G
目的:用C语连接本地数据库sid:umail,ip:127.0.0.1,用户名:umail，密码:umail,表tt1.
显示表tt1的所有记录.

思路二）
远程环境服务器1：linux es3
远程数据库：oracle9i
目的:在远程一台服务器上，再远程连接数据库，用户名和表同上
显示表tt1的所有记录.

一）思路一解决办法：

1) 查看/etc/profile文件
export ORACLE_BASE=/share/oracle
export ORACLE_HOME=$ORACLE_BASE/product/10.2.1
export ORACLE_SID=umail
export PATH=$PATH:$HOME/bin:$ORACLE_HOME/bin
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:/usr/lib:$LD_LIBRARY_PATH
export JAVA_HOME=/share/jdk
export AWT_TOOLKIT=MToolkit
作用：解决tnsnames.ora问题

2)更改$ORACLE_HOME/precomp/admin/pcscfg.cfg
sys_include=(/usr/include,/usr/lib/gcc/i486-linux-gnu/4.1.2/include,/usr/lib/gcc/i486-linux-gnu/3.4.6/include,/share/oracle/product/10.2.1/precomp/public,/usr/include/sys)
include=(/share/oracle/product/10.2.1/precomp/public)
include=/share/oracle/product/10.2.1/precomp/hdrs
include=/share/oracle/product/10.2.1/tpcc2x_2/src
include=/share/oracle/product/10.2.1/precomp/precomp/include
include=/share/oracle/product/10.2.1/precomp/oracore/include
include=/share/oracle/product/10.2.1/precomp/oracore/public
include=/share/oracle/product/10.2.1/precomp/rdbms/include
include=/share/oracle/product/10.2.1/precomp/rdbms/public
include=/share/oracle/product/10.2.1/precomp/rdbms/demo
include=/share/oracle/product/10.2.1/precomp/nlsrtl/include
include=/share/oracle/product/10.2.1/precomp/nlsrtl/public
include=/share/oracle/product/10.2.1/precomp/network_src/include
include=/share/oracle/product/10.2.1/precomp/network_src/public
include=/share/oracle/product/10.2.1/precomp/network/include
include=/share/oracle/product/10.2.1/precomp/network/public
include=/share/oracle/product/10.2.1/precomp/plsql/public
ltype=short

 

3)新test.pc文件，如下:

#include <stdio.h>

EXEC SQL INCLUDE SQLCA;

int main()
{
     //声明SQL变量
     EXEC SQL BEGIN DECLARE SECTION;
     VARCHAR user[20],pass[20],tnsname[20];
     //VARCHAR预编译后为struct { unsigned short len; unsigned char arr[20];}
     char ename[20];
     int empno;
     EXEC SQL END DECLARE SECTION;
     
     //声明C变量
     int i=0;
     
     //变量赋值
     strcpy(user.arr,"umail");
     user.len=(unsigned short)strlen((char *)user.arr);
     strcpy(pass.arr,"umail");
     pass.len=(unsigned short)strlen((char *)pass.arr);
     strcpy(tnsname.arr,"umail");
     tnsname.len=(unsigned short)strlen((char *)tnsname.arr);
     
     //连接数据库
     EXEC SQL CONNECT :user IDENTIFIED BY :pass USING :tnsname;

     EXEC SQL declare emp_cursor cursor for
                                          select id,ename from umail.tt1;

                                   
     EXEC SQL open emp_cursor;

     EXEC SQL WHENEVER NOT FOUND DO break;

     while(1)
     {
           EXEC SQL fetch emp_cursor into :empno,:ename;
           printf("the empno %d\'s name is %s\n",empno,ename);
           i=i+1;
     }
     
     printf("Yeah!We get %d records\n",i);

     EXEC SQL close emp_cursor;
     
     EXEC SQL commit work release;
}

 

3)更改tnsname文件如下:

UMAIL =
  (DEscrīptION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = umail)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DEscrīptION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

 

4)编译方法:
预编译 proc test.pc
注：这步是依赖于$ORACLE_HOME/precomp/admin/pcscfg.cfg

编译:
gcc -o test test.c $ORACLE_HOME/lib/libclntsh.so

 

思路二解决办法：

1)在远程服务器上新建一个放tnsname.ora的目录
mkdir -p /root/network/admin

2)修改tnsname.ora文件，加入远程数据库信息，如下:
db =
 (DEscrīptION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.6.217)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = umail)
    )
  )

3)将以上的tnsname.ora放入到/root/network/admin下面
scp tnsname.ora 192.168.6.197:/root/network/admin

4)在远程服务器上，将/etc/profile修改如下：
增加以下内容:
export ORACLE_HOME=/root
用su -加载环境变量

5)在本地，更改上一个实验的test.pc文件
     
原内容：
strcpy(tnsname.arr,"umail");
tnsname.len=(unsigned short)strlen((char *)tnsname.arr);

更改后的内容:
strcpy(tnsname.arr,"db");
tnsname.len=(unsigned short)strlen((char *)tnsname.arr);

6)利用本地环境重新编译test.pc

预编译 proc test.pc

scp test.c 192.168.6.197:/tmp

编译:
gcc -o test test.c /usr/lib/libclntsh.so.10.1

 

7)将test上传到远程服务器
scp test 192.168.6.197:/tmp

8)将libclntsh.so.10.1,libnnz10.so上传到远程服务器的/usr/lib下面
scp libclntsh.so.10.1 192.168.6.197:/usr/lib
scp libnnz10.so 192.168.6.197:/usr/lib

9)执行测试test
cd /tmp;./test

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附加：这是本人在网上找到的另外一个测试也通过的连接到ORACLE的程序（注意非win系统里）

int main(){ EXEC SQL BEGIN DECLARE SECTION;   char oc_passwd[101];  /*数据库密码*/   char oc_userid[101];  /*数据库用户名*/   char oc_dbname[101];  /*数据库名*/   char oc_coad[101]; EXEC SQL END DECLARE SECTION;  memset(oc_passwd, 0x00, sizeof(oc_passwd)); memset(oc_userid, 0x00, sizeof(oc_userid)); memset(oc_dbname, 0x00, sizeof(oc_dbname)); /*取数据库用户名*/ strcpy(oc_userid, "userid"); /*取数据库用户密码*/ strcpy(oc_passwd, "passwd") ; /*取数据库名*/ strcpy(oc_dbname, "dbname"); EXEC SQL CONNECT :oc_userid   IDENTIFIED BY :oc_passwd   USING :oc_dbname; if (sqlca.sqlcode != 0) {  printf("用户名[%s]密码[%s]数据库[%s]\n", oc_userid, oc_passwd, oc_dbname);  printf("连接数据库失败,sqlcode=%d\n", sqlca.sqlcode);  return -1; } /*读table取coad字段*/ memset(oc_coad, 0x00, sizeof(oc_coad)); EXEC SQL SELECT coad  INTO :oc_coad  FROM table  WHERE 1=1; if (sqlca.sqlcode == NORECORD) {  printf("查询无记录\n");  return -1; } else if (sqlca.sqlcode != 0) {  printf("查询失败,sqlcode=%d\n", sqlca.sqlcode);  return -1; } return 0;}