国外主机测评 - 国外VPS，国外服务器，国外云服务器，测评及优惠码
C语言编程在Oracle平台上的实践经验
随着大数据和云计算的兴起，Oracle作为一种关系型数据库管理系统，已经被广泛应用于企业级应用程序的开发中。在这样一个背景下，将C语言编程应用于Oracle平台上的开发，可以充分利用其优秀的性能和高效的内存管理能力，实现更加安全和可靠的数据库开发和管理。本文将就此为您介绍一些C语言编程在Oracle平台上的实践经验。
一、连接Oracle数据库
在C语言中连接Oracle数据库，我们可以使用OCI (Oracle Call Interface)来实现。OCI提供了一组API，用于协作Oracle数据库。使用OCI编写代码时，我们必须包含Oracle提供的头文件oci.h，并且链接Oracle库文件libclntsh.x.x.x.x.x。下面是一个简单的示例代码，演示了如何用C语言连接Oracle数据库：
“`c
#include
#include
#include
int mn(int argc, char *argv[]) {
OCIEnv *envhp;
OCIError *errhp;
OCIServer *srvhp;
OCISession *svchp;
OTS *authp;
sword status, major, minor, errcode;
if (OCIEnvCreate(&envhp, OCI_THREADED | OCI_OBJECT, NULL, NULL, NULL, NULL, 0, NULL)) {
printf(“OCIEnvCreate fled!\n”);
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&errhp, OCI_HTYPE_ERROR, 0, NULL)) {
printf(“OCIHandleAlloc for errhp fled!\n”);
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&srvhp, OCI_HTYPE_SERVER, 0, NULL)) {
printf(“OCIHandleAlloc for srvhp fled!\n”);
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&authp, OCI_HTYPE_SESSION, 0, NULL)) {
printf(“OCIHandleAlloc for authp fled!\n”);
exit(1);
}
if (OCILogon2(envhp, errhp, &srvhp, strlen(“username”), “username”, strlen(“password”), “password”, strlen(“tnsname”), “tnsname”, OCI_DEFAULT)) {
printf(“OCILogon2 fled!\n”);
OCIErrorGet(errhp, 1, NULL, &errcode, (OraText *)NULL, 0, OCI_HTYPE_ERROR);
printf(“Error code : %d”, errcode);
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&svchp, OCI_HTYPE_SESSION, 0, NULL)) {
printf(“OCIHandleAlloc for svchp fled!\n”);
exit(1);
}
if (OCIAttrSet(authp, OCI_HTYPE_SESSION, (void *)srvhp, 0, OCI_ATTR_SERVER, errhp)) {
printf(“OCIAttrSet for OCI_ATTR_SERVER fled!\n”);
exit(1);
}
if (OCIAttrSet(authp, OCI_HTYPE_SESSION, “username”, strlen(“username”), OCI_ATTR_USERNAME, errhp)) {
printf(“OCIAttrSet for OCI_ATTR_USERNAME fled!\n”);
exit(1);
}
if (OCIAttrSet(authp, OCI_HTYPE_SESSION, “password”, strlen(“password”), OCI_ATTR_PASSWORD, errhp)) {
printf(“OCIAttrSet for OCI_ATTR_PASSWORD fled!\n”);
exit(1);
}
if (OCISessionBegin(envhp, errhp, svchp, (ub4) OCI_CRED_RDBMS, (ub4) OCI_DEFAULT)) {
printf(“OCISessionBegin fled!\n”);
OCIErrorGet(errhp, 1, NULL, &errcode, (OraText *)NULL, 0, OCI_HTYPE_ERROR);
printf(“Error code : %d”, errcode);
exit(1);
}
printf(“Connected!\n”);
if (OCISessionEnd(envhp, errhp, svchp, OCI_DEFAULT)) {
printf(“OCISessionEnd fled!\n”);
exit(1);
}
if (OCIHandleFree(srvhp, OCI_HTYPE_SERVER)) {
printf(“OCIHandleFree for srvhp fled!\n”);
exit(1);
}
if (OCIHandleFree(svchp, OCI_HTYPE_SESSION)) {
printf(“OCIHandleFree for svchp fled!\n”);
exit(1);
}
if (OCIHandleFree(authp, OCI_HTYPE_SESSION)) {
printf(“OCIHandleFree for authp fled!\n”);
exit(1);
}
if (OCIHandleFree(errhp, OCI_HTYPE_ERROR)) {
printf(“OCIHandleFree for errhp fled!\n”);
exit(1);
}
if (OCIEnvDestroy(envhp)) {
printf(“OCIEnvDestroy fled!\n”);
exit(1);
}
printf(“Disconnected!\n”);
return 0;
}
上述代码中，我们在OCIEnvCreate函数中创建了一个OCI的环境句柄envhp，随后使用OCIHandleAlloc分配了用于处理错误的OCIError句柄errhp、用于连接服务器的OCIServer句柄srvhp、以及用于授权的OCISession句柄svchp。在OCILogon2函数中，我们使用OCI_DEFAULT作为参数打开了一个会话，并在OCISessionBegin函数中启动了一个会话。在会话结束后，我们使用OCIHandleFree分别释放了OCIServer、OCISession、OCIError句柄，最后调用OCIEnvDestroy函数销毁了OCI环境句柄。
二、执行SQL语句
OCI提供了OCIStmtPrepare、OCIStmtExecute、OCIStmtFetch等函数，用于执行SQL语句。其中，OCIStmtPrepare函数用于准备SQL语句，OCIStmtExecute函数用于执行SQL语句，OCIStmtFetch函数用于从游标中获取查询结果。
下面是一个简单的示例代码，演示了如何用C语言执行SQL语句：
```c
#include
#include
#include
int mn(int argc, char *argv[]) {
OCIEnv *envhp;
OCIError *errhp;
OCIServer *srvhp;
OCISession *svchp;
OTS *authp;
OCIStmt *stmthp;
OCIDefine *defhp;
sword status, major, minor, errcode;
int empno, sal;
if (OCIEnvCreate(&envhp, OCI_THREADED | OCI_OBJECT, NULL, NULL, NULL, NULL, 0, NULL)) {
printf("OCIEnvCreate fled!\n");
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&errhp, OCI_HTYPE_ERROR, 0, NULL)) {
printf("OCIHandleAlloc for errhp fled!\n");
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&srvhp, OCI_HTYPE_SERVER, 0, NULL)) {
printf("OCIHandleAlloc for srvhp fled!\n");
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&authp, OCI_HTYPE_SESSION, 0, NULL)) {
printf("OCIHandleAlloc for authp fled!\n");
exit(1);
}
if (OCILogon2(envhp, errhp, &srvhp, strlen("username"), "username", strlen("password"), "password", strlen("tnsname"), "tnsname", OCI_DEFAULT)) {
printf("OCILogon2 fled!\n");
OCIErrorGet(errhp, 1, NULL, &errcode, (OraText *)NULL, 0, OCI_HTYPE_ERROR);
printf("Error code : %d", errcode);
exit(1);
}
if (OCIHandleAlloc(envhp, (void **)&svchp, OCI_HTYPE_SESSION, 0, NULL)) {
printf("OCIHandleAlloc for svchp fled!\n");
exit(1);
}
if (OCIAttrSet(authp, OCI_HTYPE_SESSION, (void *)srvhp, 0, OCI_ATTR_SERVER, errhp)) {
printf("OCIAttrSet for OCI_ATTR_SERVER fled!\n");
exit(1);
}
if (OCIAttrSet(authp, OCI_HTYPE_SESSION, "username", strlen("username"), OCI_ATTR_USERNAME, errhp)) {
printf("OCIAttrSet for OCI_ATTR_USERNAME fled!\n");
exit(1);
}
if (OCIAttrSet(authp, OCI_HTYPE_SESSION, "password", strlen("password"), OCI_ATTR_PASSWORD, errhp)) {
printf("OCIAttrSet for OCI_ATTR_PASSWORD fled!\n");
exit(1);
}
if (OCISessionBegin(envhp,
