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如何利用C语言高效连接和操作Oracle网络数据库？

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行业动态
2025-01-25
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Oracle数据库是甲骨文公司开发的关系数据库管理系统，具有强稳定性、可移植性、高效率等特点，适用于各类大、中、小型微机环境。

在C语言中连接Oracle数据库，通常需要使用OCI（Oracle Call Interface）或ODBC（Open Database Connectivity）等接口，以下是详细的步骤和示例代码：

如何利用C语言高效连接和操作Oracle网络数据库？第1张

安装和配置

1、安装Oracle客户端：首先需要安装Oracle Instant Client，它是一个轻量级的客户端软件，包含所有必要的动态链接库和头文件，使得C程序可以通过OCI与Oracle数据库进行通信。

2、配置环境变量：将Oracle Instant Client的安装目录添加到系统的环境变量中，以便C程序能够找到所需的库文件。

编写连接代码

以下是一个使用OCI连接Oracle数据库的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <oci.h>
void checkerr(OCIError *errhp, sword status) {
    text errbuf[512];
    sb4 errcode = 0;
    switch (status) {
        case OCI_SUCCESS:
            break;
        case OCI_SUCCESS_WITH_INFO:
            printf("OCI_SUCCESS_WITH_INFOn");
            break;
        case OCI_NO_DATA:
        case OCI_NEED_DATA:
        case OCI_ERROR:
            OCIErrorGet((dvoid *)errhp, (ub4) 1, (text *) NULL, &errcode, (text *) errbuf, (ub4) sizeof(errbuf), (ub4) OCI_HTYPE_ERROR);
            printf("OCI_ERROR: %sn", errbuf);
            break;
        case OCI_INVALID_HANDLE:
            printf("OCI_INVALID_HANDLEn");
            break;
        case OCI_STILL_EXECUTING:
            printf("OCI_STILL_EXECUTINGn");
            break;
        case OCI_CONTINUE:
            printf("OCI_CONTINUEn");
            break;
        default:
            printf("Unknown statusn");
    }
}
int main() {
    OCIEnv *envhp;
    OCIError *errhp;
    OCISvcCtx *svchp;
    OCIStmt *stmthp;
    OCIDefine *defnp;
    OCIServer *srvhp;
    OCIAuthInfo *authinfohp;
    OCISession *usrhp;
    text *username = (text *) "scott";
    text *password = (text *) "tiger";
    text *dbname = (text *) "localhost:1521/orclpdb";
    text sql[] = "SELECT * FROM employees";
    sword status;
    // 初始化OCI环境
    OCIEnvCreate(&envhp, OCI_DEFAULT, 0, (dvoid *) 0, (dvoid *) 0, (size_t) 0, (size_t) 0);
    OCIHandleAlloc(envhp, (dvoid *) &errhp, OCI_HTYPE_ERROR, 0, (dvoid *) 0);
    // 创建和配置服务上下文
    OCIHandleAlloc(envhp, (dvoid *) &svchp, OCI_HTYPE_SVCCTX, 0, (dvoid *) 0);
    OCIHandleAlloc(envhp, (dvoid *) &srvhp, OCI_HTYPE_SERVER, 0, (dvoid *) 0);
    OCIHandleAlloc(envhp, (dvoid *) &authinfohp, OCI_HTYPE_AUTHINFO, 0, (dvoid *) 0);
    OCIHandleAlloc(envhp, (dvoid *) &usrhp, OCI_HTYPE_SESSION, 0, (dvoid *) 0);
    // 设置用户名、密码和数据库名
    OCIAttrSet(authinfohp, OCI_HTYPE_AUTHINFO, username, strlen((char *) username), OCI_ATTR_USERNAME, errhp);
    OCIAttrSet(authinfohp, OCI_HTYPE_AUTHINFO, password, strlen((char *) password), OCI_ATTR_PASSWORD, errhp);
    // 连接到数据库
    status = OCILogon(envhp, errhp, svchp, authinfohp, dbname, strlen((char *) dbname));
    if (status != OCI_SUCCESS) {
        printf("Failed to connect to database.
");
        return 1;
    }
    // 准备SQL语句
    OCIHandleAlloc(envhp, (dvoid *) &stmthp, OCI_HTYPE_STMT, 0, (dvoid *) 0);
    status = OCIStmtPrepare(stmthp, errhp, (OraText *) sql, strlen((char *) sql), OCI_NTV_SYNTAX, OCI_DEFAULT);
    if (status != OCI_SUCCESS) {
        printf("Failed to prepare SQL statement.
");
        return 1;
    }
    // 执行SQL语句
    status = OCIStmtExecute(svchp, stmthp, errhp, 1, 0, (OCISnapshot *) NULL, (OCISnapshot *) NULL, OCI_DEFAULT);
    if (status != OCI_SUCCESS) {
        printf("Failed to execute SQL statement.
");
        return 1;
    }
    // 处理结果集
    char result[100];
    OCIHandleAlloc(envhp, (dvoid *) &defnp, OCI_HTYPE_DEFINE, 0, (dvoid *) 0);
    OCIDefineByPos(stmthp, &defnp, errhp, 1, (dvoid *) &result, sizeof(result), SQLT_STR, NULL, NULL, NULL, OCI_DEFAULT);
    while ((status = OCIStmtFetch(stmthp, errhp, 1, OCI_FETCH_NEXT, OCI_DEFAULT)) == OCI_SUCCESS) {
        printf("Result: %s
", result);
    }
    // 清理资源
    OCIHandleFree(stmthp, OCI_HTYPE_STMT);
    OCILogoff(svchp, errhp);
    OCIHandleFree(svchp, OCI_HTYPE_SVCCTX);
    OCIHandleFree(errhp, OCI_HTYPE_ERROR);
    OCIHandleFree(envhp, OCI_HTYPE_ENV);
    return 0;
}