C语言在Oracle环境的应用（c 能用oracle）

C语言在Oracle环境的应用

在数据库开发中，C语言是一种非常重要的编程语言。而Oracle则是当今最为流行的关系数据库管理系统(RDBMS)之一。因此，将C语言应用到Oracle环境中，能够使得开发者更加高效地开发、维护和管理Oracle数据库。本文将介绍C语言在Oracle环境下的应用。

一、C语言连接Oracle数据库

C语言连接Oracle数据库需要使用Oracle提供的OCI库。OCI为Oracle Call Interface的缩写，是Oracle提供的访问Oracle数据库的标准API接口。在安装Oracle时，OCI库已经随之安装。以下是C语言连接Oracle数据库的代码示例：

“`c

#include

#include

#include

int mn()

{

OCIEnv *envhp;

OCIError *errhp;

OCIServer *srvhp;

OCISession *authhp;

OCIInitialize(OCI_ENV_DEFAULT);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &errhp, OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &srvhp, OCI_HTYPE_SERVER, (size_t) 0, (dvoid **) 0);

OCIServerAttach(srvhp, errhp, “”, strlen(“”), OCI_DEFAULT);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &authhp, OCI_HTYPE_SESSION, (size_t) 0, (dvoid **) 0);

OCIAttrSet((dvoid *) authhp, OCI_HTYPE_SESSION, (dvoid *) “”, strlen(“”), OCI_ATTR_USERNAME, errhp);

OCIAttrSet((dvoid *) authhp, OCI_HTYPE_SESSION, (dvoid *) “”, strlen(“”), OCI_ATTR_PASSWORD, errhp);

OCISessionBegin(srvhp, errhp, authhp, OCI_CRED_RDBMS, OCI_DEFAULT);

printf(“Connected to Oracle database successfully!”);

OCIHandleFree((dvoid *) authhp, OCI_HTYPE_SESSION);

OCISessionEnd(srvhp, errhp, authhp, OCI_DEFAULT);

OCIHandleFree((dvoid *) srvhp, OCI_HTYPE_SERVER);

OCIHandleFree((dvoid *) errhp, OCI_HTYPE_ERROR);

OCIEnvCleanup();

return 0;

}

二、C语言执行SQL语句

连接Oracle数据库之后，就可以使用C语言执行SQL语句。以下是C语言执行SQL语句的代码示例：

```c
#include 
#include 
#include 
int mn()
{
   OCIEnv *envhp;
   OCIError *errhp;
   OCISvcCtx *svchp;
   OCIStmt *stmthp;
   OCIDefine *defnhp;
   OCIParam *paramhp;
   char username[20];
   char sql_query[100] = "SELECT USERNAME FROM USER_USERS WHERE ROWNUM = 1";
   OCIInitialize(OCI_ENV_DEFAULT);

   OCIHandleAlloc((dvoid *) envhp, (dvoid **) &errhp, OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0);
   OCIHandleAlloc((dvoid *) envhp, (dvoid **) &svchp, OCI_HTYPE_SVCCTX, (size_t) 0, (dvoid **) 0);
   OCIAttrSet((dvoid *) svchp, OCI_HTYPE_SVCCTX, (dvoid *) srvhp, (ub4) 0, OCI_ATTR_SERVER, errhp);

   OCIHandleAlloc((dvoid *) envhp, (dvoid **) &stmthp, OCI_HTYPE_STMT, (size_t) 0, (dvoid **) 0);

   OCIStmtPrepare(stmthp, errhp, sql_query, strlen(sql_query), OCI_DEFAULT);
   OCIStmtExecute(svchp, stmthp, errhp, (ub4) 0, (ub4) 0, (OCISnapshot *) NULL, (OCISnapshot *) NULL, OCI_DEFAULT);
   OCIHandleAlloc((dvoid *) envhp, (dvoid **) &defnhp, OCI_HTYPE_DEFINE, (size_t) sizeof(username), (dvoid **) 0);
   OCIAttrSet((dvoid *) defnhp, OCI_HTYPE_DEFINE, (dvoid *) &username, (ub4 *) sizeof(username), OCI_ATTR_DATA, errhp);
   OCIStmtFetch(stmthp, errhp, (ub4) 1, OCI_DEFAULT, OCI_DEFAULT);

   printf("Username: %s", username);

   OCIHandleFree((dvoid *) defnhp, OCI_HTYPE_DEFINE);
   OCIHandleFree((dvoid *) stmthp, OCI_HTYPE_STMT);
   OCIHandleFree((dvoid *) svchp, OCI_HTYPE_SVCCTX);
   OCIHandleFree((dvoid *) errhp, OCI_HTYPE_ERROR);
   OCIEnvCleanup();

   return 0;
}

三、C语言使用Oracle的函数和存储过程

C语言可以使用Oracle提供的函数和存储过程。以下是C语言使用Oracle的函数和存储过程的代码示例：

“`c

#include

#include

#include

int mn()

{

OCIEnv *envhp;

OCIError *errhp;

OCISvcCtx *svchp;

OCIStmt *stmthp;

OCIDefine *defnhp;

OCIParam *paramhp;

OCIInt2 byte_order;

int num;

OCIInitialize(OCI_ENV_DEFAULT);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &errhp, OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &svchp, OCI_HTYPE_SVCCTX, (size_t) 0, (dvoid **) 0);

OCIAttrSet((dvoid *) svchp, OCI_HTYPE_SVCCTX, (dvoid *) srvhp, (ub4) 0, OCI_ATTR_SERVER, errhp);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &stmthp, OCI_HTYPE_STMT, (size_t) 0, (dvoid **) 0);

/* 调用Oracle的函数 */

OCINumberFromInt(errhp, &num, sizeof(num), OCI_NUMBER_SIGNED, &byte_order);

OCINumberToInt(errhp, &num, sizeof(num), OCI_NUMBER_SIGNED, &byte_order);

/* 调用Oracle的存储过程 */

char procedure[100] = “BEGIN MY_PROCEDURE(:in_param, :out_param); END;”;

OCIStmtPrepare(stmthp, errhp, procedure, strlen(procedure), OCI_NTV_SYNTAX);

OCIParamGet(stmthp, OCI_HTYPE_STMT, errhp, (void **) &paramhp, (ub4) 1);

OCIDefineByPos(stmthp, &defnhp, errhp, (ub4) 2, (void *) &out_param, sizeof(out_param), SQLT_INT, (void *)&ind, (ub2 *) 0, (ub2 *) 0, OCI_DEFAULT);

OCIBindByPos(stmthp, &paramhp, errhp, (ub4) 1, (void *) &in_param, sizeof(in_param), SQLT_INT, (void *) &ind, (ub2 *) 0, (ub2 *) 0, (ub4) 0, (ub4 *) 0, OCI_DEFAULT);

OCIStmtExecute(svchp, stmthp, errhp, (ub4) 1, (ub4) 0, (OCISnapshot *) NULL, (OCISnapshot *) NULL, OCI_DEFAULT);

OCIHandleFree((dvoid *) defnhp, OCI_HTYPE_DEFINE);

OCIHandleFree((dvoid *) stmthp, OCI_HTYPE_STMT);

OCIHandleFree((dvoid *) svchp, OCI_HTYPE_SVCCTX);

OCIHandleFree((dvoid *) errhp, OCI_HTYPE_ERROR);

OCIEnvCleanup();

return 0;

}

总体来看，C语言在Oracle环境中的应用非常广泛，不仅可以实现连接数据库、执行SQL语句，还可以调用Oracle的函数和存储过程。以上是C语言在Oracle环境下的基本应用，希望对读者有所帮助。