c oracle 客户端

C语言作为一门广泛应用的编程语言，一直都有着重要的地位。而Oracle作为一个世界级数据库管理系统，也被广泛应用于各种应用中。在实际应用过程中，C语言和Oracle的结合，也是非常普遍的。本文将就C语言与Oracle客户端的关联，进行详细的阐述。

为了更深入地理解C语言与Oracle客户端的关系，我们以C语言连接Oracle数据库中的一个表为例进行说明。在这个例子当中，我们将通过C语言连接Oracle数据库，并且使用OCI（Oracle Call Interface）访问其中的一个表。代码流程如下：

OCIEnv * envhp;
    OCIError * errhp;
    OCIServer * srvhp;
    OCIStmt * stmthp;
    OCIStmt * stmthp_sel;
    OCIDefine * defnhp = NULL;
    oraub8       myARRAY[MYBUFFSZ];
    OCIParam *colhp;
    text      colname[MAX_COLNAMELEN + 1] ;
    *envhp = NULL ;
    *errhp = NULL ;
    *srvhp = NULL ;
    *stmthp = NULL ;
    /* 创建运行环境 */OCIEnvCreate(envhp, OCI_OBJENV , (dvoid *) 0,(dvoid * (*)(dvoid *, size_t)) 0,(dvoid * (*)(dvoid *, dvoid *, size_t)) 0,(void (*)(dvoid *, dvoid *)) 0,0, (dvoid **) 0);
    /* 创建错误处理环境 */OCIHandleAlloc((dvoid *)envhp, (dvoid **)&
    errhp, (ub4) OCI_HTYPE_ERROR, 0, (dvoid **)0);
    /* 创建服务器环境 */OCIHandleAlloc((dvoid *)envhp, (dvoid **)&
    srvhp, (ub4) OCI_HTYPE_SERVER, 0, (dvoid **)0);
    /* 进行连接 */OCIAttrSet((dvoid *)srvhp, (ub4)OCI_HTYPE_SERVER, (dvoid *)"ORACLE_SID", strlen("ORACLE_SID"), OCI_ATTR_SERVER, (OCIError *)errhp);
    OCIAttrSet((dvoid *)srvhp, (ub4)OCI_HTYPE_SERVER, (dvoid *)"ORACLE_SERVERNAME", strlen("ORACLE_SERVERNAME"), OCI_ATTR_SERVER, (OCIError *)errhp);
    OCILogon2(envhp, errhp, &
    srvhp, (OraText *)"username", strlen("username"), (OraText *)"password", strlen("password"), (OraText *)"RACDB", strlen("RACDB"), OCI_DEFAULT)/* SQL准备 */OCIHandleAlloc((dvoid *)envhp, (dvoid **)&
    stmthp, (ub4) OCI_HTYPE_STMT, 0, (dvoid **)0);
    /* 建立命令 */OCIStmtPrepare(stmthp, errhp, (text *)"select * from yourtablename", strlen("select * from yourtablename"),(ub4) OCI_NTV_SYNTAX, (ub4) OCI_DEFAULT);
    /* 执行命令 */OCIStmtExecute(svchp, stmthp, errhp, (ub4) 1, (ub4) 0, (OCISnapshot *) NULL,(OCISnapshot *) NULL, OCI_DEFAULT);
    /* 获取返回结果 */OCIParamGet(stmthp, (ub4) OCI_HTYPE_STMT, errhp, (dvoid **) &
    colhp, (ub4) 1);
    ub2 mycolcnt ;
    OCIAttrGet((dvoid *) colhp, (ub4)OCI_DTYPE_PARAM, (dvoid *)&
    mycolcnt, (ub4 *) 0, (ub4)OCI_ATTR_NUM_COLS, errhp);
    for( i = 1 ;
     i

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