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/oracleexport ORACLE_HOME=$ORACLE_BASE/product/10.2.1export ORACLE_SID=umailexport PATH=$PATH:$HOME/bin:$ORACLE_HOME/binexport LD_LIBRARY_PATH=$ORACLE_HOME/lib:/usr/lib:$LD_LIBRARY_PATHexport JAVA_HOME=/share/jdkexport 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/hdrsinclude=/share/oracle/product/10.2.1/tpcc2x_2/srcinclude=/share/oracle/product/10.2.1/precomp/precomp/includeinclude=/share/oracle/product/10.2.1/precomp/oracore/includeinclude=/share/oracle/product/10.2.1/precomp/oracore/publicinclude=/share/oracle/product/10.2.1/precomp/rdbms/includeinclude=/share/oracle/product/10.2.1/precomp/rdbms/publicinclude=/share/oracle/product/10.2.1/precomp/rdbms/demoinclude=/share/oracle/product/10.2.1/precomp/nlsrtl/includeinclude=/share/oracle/product/10.2.1/precomp/nlsrtl/publicinclude=/share/oracle/product/10.2.1/precomp/network_src/includeinclude=/share/oracle/product/10.2.1/precomp/network_src/publicinclude=/share/oracle/product/10.2.1/precomp/network/includeinclude=/share/oracle/product/10.2.1/precomp/network/publicinclude=/share/oracle/product/10.2.1/precomp/plsql/publicltype=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/libscp libnnz10.so 192.168.6.197:/usr/lib 9)执行测试testcd /tmp;./test