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
