C程序实现Oracle操作（c 实现oracle）

C程序实现Oracle操作

在现代化的企业级应用开发中，使用Oracle数据库的公司并不鲜见。它的功能强大，可运行的应用程序数量很大，使用了许多开发语言。其中，C程序是一个广泛使用的语言，因为它快速、轻便且可以直接访问底层系统资源。然而，许多开发人员发现，在使用C程序时访问Oracle数据库是一件有些棘手的事情。今天，我们将介绍一些方法，帮助您轻松地在C程序中执行Oracle数据库操作。

前置条件

在访问Oracle数据库之前，我们需要下载和安装Oracle客户端。可以从Oracle官方网站下载适用于不同平台的适当版本。步骤如下：

1.访问https://www.oracle.com/technetwork/database/enterprise-edition/downloads/index.html。

2.选择正确的版本（Microsoft Windows系统或Linux等），然后单击下载。

3.在安装过程中，根据安装向导的提示进行操作。需要注意的是，请确保在安装过程中选择所有必要的选项，包括Net Service Name、Oracle Home和TNS Names等。

连接到Oracle数据库

在C程序中连接到Oracle数据库，需要使用Oracle提供的OCI库。OCI（Oracle Call Interface）是一个C语言编写的本机库，它允许开发人员编写C语言程序来访问Oracle数据库。

下面是一个连接Oracle数据库的简单C程序。它使用连接字符串、用户名和密码等参数连接到Oracle数据库，并检查连接是否成功：

#include 
#include 
#include 
int mn(int argc, char *argv[])
{
    OCIEnv *envhp;
    OCIServer *srvhp;
    OCIError *errhp;
    OCISession *usrhp;
    OCISvcCtx *svchp;

    sword status;

    char *username = "your_username";
    char *password = "your_password";
    char *dbname = "//your_hostname:port/your_service_name"; //Connection string

    status = OCIEnvCreate(&envhp, OCI_DEFAULT, (void *)0, (void *(*)(void *, size_t))0, (void *(*)(void *, void *, size_t))0, (void (*)(void *, void *))0, (size_t)0, (void **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIEnvCreate.");
        exit(-1);
    }
    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&errhp, OCI_HTYPE_ERROR, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&srvhp, OCI_HTYPE_SERVER, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    (void)OCIAttrSet((dvoid *)srvhp, OCI_HTYPE_SERVER, (dvoid *)dbname, (ub4)strlen((const char *)dbname), OCI_ATTR_SERVER_DNS, errhp);

    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&svchp, OCI_HTYPE_SVCCTX, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    (void)OCIAttrSet((dvoid *)svchp, OCI_HTYPE_SVCCTX, (dvoid *)srvhp, (ub4)0, OCI_ATTR_SERVER, errhp);

    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&usrhp, OCI_HTYPE_SESSION, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    (void)OCIAttrSet((dvoid *)usrhp, OCI_HTYPE_SESSION, (dvoid *)username, (ub4)strlen((const char *)username), OCI_ATTR_USERNAME, errhp);
    (void)OCIAttrSet((dvoid *)usrhp, OCI_HTYPE_SESSION, (dvoid *)password, (ub4)strlen((const char *)password), OCI_ATTR_PASSWORD, errhp);
    status = OCISessionBegin(svchp, errhp, usrhp, OCI_CRED_RDBMS, OCI_DEFAULT);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCISessionBegin.");
        exit(-1);
    }
    status = OCIAttrSet((dvoid *)svchp, OCI_HTYPE_SVCCTX, (dvoid *)usrhp, (ub4)0, OCI_ATTR_SESSION, errhp);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIAttrSet.");
        exit(-1);
    }
    printf("Connected to database successfully.");

    return 0;
}

执行SQL查询

一旦连接到Oracle数据库，我们可以执行SQL查询语句并检索数据。下面是一个简单的程序，从employees表中检索所有员工的姓名和工资：

#include 
#include 
#include 
#include 
int mn(int argc, char *argv[])
{
    OCIEnv *envhp;
    OCIServer *srvhp;
    OCIError *errhp;
    OCISession *usrhp;
    OCISvcCtx *svchp;
    OCIStmt *stmthp;
    OCIDefine *defhp;

    sword status;

    char *username = "your_username";
    char *password = "your_password";
    char *dbname = "//your_hostname:port/your_service_name"; //Connection string

    char *select_query = "SELECT first_name, last_name, salary FROM employees";

    status = OCIEnvCreate(&envhp, OCI_DEFAULT, (void *)0, (void *(*)(void *, size_t))0, (void *(*)(void *, void *, size_t))0, (void (*)(void *, void *))0, (size_t)0, (void **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIEnvCreate.");
        exit(-1);
    }
    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&errhp, OCI_HTYPE_ERROR, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&srvhp, OCI_HTYPE_SERVER, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    (void)OCIAttrSet((dvoid *)srvhp, OCI_HTYPE_SERVER, (dvoid *)dbname, (ub4)strlen((const char *)dbname), OCI_ATTR_SERVER_DNS, errhp);

    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&svchp, OCI_HTYPE_SVCCTX, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    (void)OCIAttrSet((dvoid *)svchp, OCI_HTYPE_SVCCTX, (dvoid *)srvhp, (ub4)0, OCI_ATTR_SERVER, errhp);

    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&usrhp, OCI_HTYPE_SESSION, (size_t)0, (dvoid **)0);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIHandleAlloc.");
        exit(-1);
    }
    (void)OCIAttrSet((dvoid *)usrhp, OCI_HTYPE_SESSION, (dvoid *)username, (ub4)strlen((const char *)username), OCI_ATTR_USERNAME, errhp);
    (void)OCIAttrSet((dvoid *)usrhp, OCI_HTYPE_SESSION, (dvoid *)password, (ub4)strlen((const char *)password), OCI_ATTR_PASSWORD, errhp);
    status = OCISessionBegin(svchp, errhp, usrhp, OCI_CRED_RDBMS, OCI_DEFAULT);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCISessionBegin.");
        exit(-1);
    }
    status = OCIAttrSet((dvoid *)svchp, OCI_HTYPE_SVCCTX, (dvoid *)usrhp, (ub4)0, OCI_ATTR_SESSION, errhp);
    if (status != OCI_SUCCESS)
    {
        printf("Error in OCIAttrSet.");
        exit(-1);
    }
    status = OCIHandleAlloc((dvoid *)envhp, (dvoid **)&stmthp, OCI_HTYPE_STMT, (size_t)0