oracle proc 编程是在我的概念中是非常陌生的，学习了一天下来发现这东西真的好古老，但是依然健壮、稳定，其中间是编辑一个 .pc 的文件使用 proc 进行预处理，预处理后生成一个真正的.c文件，此时再由 gcc 去编译成一个可执行文件运行。因为 proc 涉及到的知识较多，我无法整理到几篇博文中就概述这些所涉及的知识，所以只能总结代码做好注释防止以后自己需要时忘记。如果有想进一步了解 proc 编程的，可以买名为“Oracle9I ProC C++编程指南”。包括 oracle 的环境搭建也并不是我们讨论的重点，如果有精力的话，我会给大家编写类似的教程。
最小化实现代码
#include <stdio.h>
#include “sqlca.h”// 包含 proc 头文件
EXEC SQL BEGIN DECLARE SECTION;
char* serversid = “scott/tiger@orcl”;// 定义宿主变量
EXEC SQL END DECLARE SECTION;
int main(int argc, char* argv)
{
int ret = 0;
printf(“connect server str = %s\n”, serversid);
EXEC SQL connect :serversid;// 连接服务器
if (sqlca.sqlcode != 0)// 错误处理机制，后文会有详细介绍
{
ret = sqlca.sqlcode;
printf(“connect error…errcode = %d\n”, ret);
return ret;
}
printf(“connect oracler server success…\n”);
EXEC SQL commit release;// 提交并关闭连接
return 0;
}
使用 proc 命令进行编译，编译结果如下：
[oracle@localhost 0723]$ proc hello.pc
Pro*C/C++: Release 11.2.0.1.0 - Production on Fri Jul 24 13:20:03 2015
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
System default option values taken from: /home/oracle_11/app/oracle/product/11.2.0/db_1/precomp/admin/pcscfg.cfg
此时会在当前目录下生成一个预处理过的 .c 文件，.c文件的内容如下：
/* Result Sets Interface */
#ifndef SQL_CRSR
define SQL_CRSR
struct sql_cursor
{
unsigned int curocn;
void *ptr1;
void *ptr2;
unsigned int magic;
};
typedef struct sql_cursor sql_cursor;
typedef struct sql_cursor SQL_CURSOR;
#endif /* SQL_CRSR */
/* Thread Safety */
typedef void * sql_context;
typedef void * SQL_CONTEXT;
/* Object support */
struct sqltvn
{
unsigned char *tvnvsn;
unsigned short tvnvsnl;
unsigned char *tvnnm;
unsigned short tvnnml;
unsigned char *tvnsnm;
unsigned short tvnsnml;
};
typedef struct sqltvn sqltvn;
struct sqladts
{
unsigned int adtvsn;
unsigned short adtmode;
unsigned short adtnum;
sqltvn adttvn[1];
};
typedef struct sqladts sqladts;
static struct sqladts sqladt = {
1,1,0,
};
/* Binding to PL/SQL Records */
struct sqltdss
{
unsigned int tdsvsn;
unsigned short tdsnum;
unsigned char *tdsval[1];
};
typedef struct sqltdss sqltdss;
static struct sqltdss sqltds =
{
1,
0,
};
/* File name & Package Name */
struct sqlcxp
{
unsigned short fillen;
char filnam[9];
};
static struct sqlcxp sqlfpn =
{
8,
“hello.pc”
};
static unsigned int sqlctx = 18323;
static struct sqlexd {
unsigned long sqlvsn;
unsigned int arrsiz;
unsigned int iters;
unsigned int offset;
unsigned short selerr;
unsigned short sqlety;
unsigned int occurs;
short *cud;
unsigned char *sqlest;
char *stmt;
sqladts *sqladtp;
sqltdss *sqltdsp;
unsigned char **sqphsv;
unsigned long *sqphsl;
int *sqphss;
short **sqpind;
int *sqpins;
unsigned long *sqparm;
unsigned long **sqparc;
unsigned short *sqpadto;
unsigned short *sqptdso;
unsigned int sqlcmax;
unsigned int sqlcmin;
unsigned int sqlcincr;
unsigned int sqlctimeout;
unsigned int sqlcnowait;
int sqfoff;
unsigned int sqcmod;
unsigned int sqfmod;
unsigned char *sqhstv[4];
unsigned long sqhstl[4];
int sqhsts[4];
short *sqindv[4];
int sqinds[4];
unsigned long sqharm[4];
unsigned long *sqharc[4];
unsigned short sqadto[4];
unsigned short sqtdso[4];
} sqlstm = {12,4};
/* SQLLIB Prototypes */
extern sqlcxt ( void **, unsigned int *,
struct sqlexd *, struct sqlcxp * );
extern sqlcx2t( void **, unsigned int *,
struct sqlexd *, struct sqlcxp * );
extern sqlbuft( void **, char * );
extern sqlgs2t( void **, char * );
extern sqlorat( void **, unsigned int *, void * );
/* Forms Interface */
static int IAPSUCC = 0;
static int IAPFAIL = 1403;
static int IAPFTL = 535;
extern void sqliem( unsigned char *, signed int * );
typedef struct { unsigned short len; unsigned char arr[1]; } VARCHAR;
typedef struct { unsigned short len; unsigned char arr[1]; } varchar;
/* CUD (Compilation Unit Data) Array */
static short sqlcud0[] =
{12,4130,1,0,0,
5,0,0,0,0,0,27,13,0,0,4,4,0,1,0,1,97,0,0,1,10,0,0,1,10,0,0,1,10,0,0,
36,0,0,2,0,0,30,22,0,0,0,0,0,1,0,
};
#include <stdio.h>
#include “sqlca.h”
/* EXEC SQL BEGIN DECLARE SECTION; */
char* serversid = “scott/tiger@orcl”;// 定义宿主变量
/* EXEC SQL END DECLARE SECTION; */
int main(int argc, char* argv[])
{
int ret = 0;
printf(“serversid: %s\n”, serversid);// 打印一下服务器的连接地址字符串
/* EXEC SQL CONNECT :serversid; */
{
struct sqlexd sqlstm;
sqlstm.sqlvsn = 12;
sqlstm.arrsiz = 4;
sqlstm.sqladtp = &sqladt;
sqlstm.sqltdsp = &sqltds;
sqlstm.iters = (unsigned int )10;
sqlstm.offset = (unsigned int )5;
sqlstm.cud = sqlcud0;
sqlstm.sqlest = (unsigned char *)&sqlca;
sqlstm.sqlety = (unsigned short)4352;
sqlstm.occurs = (unsigned int )0;
sqlstm.sqhstv[0] = (unsigned char *)serversid;
sqlstm.sqhstl[0] = (unsigned long )0;
sqlstm.sqhsts[0] = ( int )0;
sqlstm.sqindv[0] = ( short *)0;
sqlstm.sqinds[0] = ( int )0;
sqlstm.sqharm[0] = (unsigned long )0;
sqlstm.sqadto[0] = (unsigned short )0;
sqlstm.sqtdso[0] = (unsigned short )0;
sqlstm.sqphsv = sqlstm.sqhstv;
sqlstm.sqphsl = sqlstm.sqhstl;
sqlstm.sqphss = sqlstm.sqhsts;
sqlstm.sqpind = sqlstm.sqindv;
sqlstm.sqpins = sqlstm.sqinds;
sqlstm.sqparm = sqlstm.sqharm;
sqlstm.sqparc = sqlstm.sqharc;
sqlstm.sqpadto = sqlstm.sqadto;
sqlstm.sqptdso = sqlstm.sqtdso;
sqlstm.sqlcmax = (unsigned int )100;
sqlstm.sqlcmin = (unsigned int )2;
sqlstm.sqlcincr = (unsigned int )1;
sqlstm.sqlctimeout = (unsigned int )0;
sqlstm.sqlcnowait = (unsigned int )0;
sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
}
// 连接服务器
if (sqlca.sqlcode != 0)// 容错处理，后面会有更详细的文章介绍
{
ret = sqlca.sqlcode;
printf(“connect oracle error… code = %d\n”, ret);
return ret;
}
printf(“connect oracle success…\n”);
/* EXEC SQL COMMIT RELEASE; */
{
struct sqlexd sqlstm;
sqlstm.sqlvsn = 12;
sqlstm.arrsiz = 4;
sqlstm.sqladtp = &sqladt;
sqlstm.sqltdsp = &sqltds;
sqlstm.iters = (unsigned int )1;
sqlstm.offset = (unsigned int )36;
sqlstm.cud = sqlcud0;
sqlstm.sqlest = (unsigned char *)&sqlca;
sqlstm.sqlety = (unsigned short)4352;
sqlstm.occurs = (unsigned int )0;
sqlcxt((void **)0, &sqlctx, &sqlstm, &sqlfpn);
}
// 提交(commit)并关闭(release)连接
return 0;
}
这是由 proc 预处理过后的 .c 文件，只不过是将我们之前编写的 pc 文件中的一些 EXE SQL … 等关键字替换成了真正的 c 语言执行语句。最后我们需要使用 gcc 来编译它。如果你直接编译的话，会收到如下报错：
[oracle@localhost 0723]$ gcc hello.c -o hello
/tmp/cchZbCeQ.o: In function `main’:
hello.c:(.text+0x86): undefined reference to `ECPGget_sqlca’
hello.c:(.text+0x1ed): undefined reference to `sqlcxt’
hello.c:(.text+0x1f2): undefined reference to `ECPGget_sqlca’
hello.c:(.text+0x200): undefined reference to `ECPGget_sqlca’
hello.c:(.text+0x27f): undefined reference to `ECPGget_sqlca’
hello.c:(.text+0x2b7): undefined reference to `sqlcxt’
这提示的意思是找不到动态库，所以我们需要手动指定动态库和头文件所在路径。正确的编译方法如下：
gcc hello.c -o hello -I $ORACLE_HOME/precomp/public -L $ORACLE_HOME/lib -l clntsh
编译完成后运行程序，如果提示连接成功，那么证明你的程序就可以正常连接 oracle 服务器了：
[oracle@localhost 0723]$ ./hello
serversid: scott/tiger@orcl
connect oracle success…