最近在搞C语言连接Oracle、DB2数据库，现把C连接Oracle的文章总结下：
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
