Oracle连接释放C语言实现（c oracle释放连接）

Oracle连接释放：C语言实现

在使用Oracle数据库的过程中，连接的释放是十分重要的一步，能够有效地释放资源，提高数据库的效率。本文将介绍如何使用C语言实现Oracle连接的释放。

1. Oracle连接的创建

在开始介绍连接的释放之前，先简单介绍下连接的创建。在C语言中，使用Oracle提供的OCI库来创建和管理连接。下面是一个简单的Oracle连接创建的代码示例。

OCIEnv *envhp;
OCIError *errhp;
OCIServer *svrhp;
OCIServiceContext *svchp;
OCISession *authp;
OCIStmt *stmthp;
OCIDefine *defhp;
OCIParam *prmhp;
OCIDateTime *dthp;
OCIBind *bndhp;
OCIResult *res;
char *user = "user";
char *pwd = "pwd";
char *db = "db";

OCIInitialize((ub4)OCI_OBJECT, (dvoid*)0,
             (dvoid* (*)(dvoid*, size_t)) 0,
             (dvoid* (*)(dvoid*, dvoid*, size_t))0,
             (void (*)(dvoid*, dvoid*)) 0);
OCIEnvCreate((OCIEnv **)&envhp, (ub4)OCI_OBJECT,
             (dvoid *)0, (dvoid * (*)(dvoid *, size_t))0,
             (dvoid * (*)(dvoid *, dvoid *, size_t))0,
             (void (*)(dvoid *, dvoid *))0,
             (size_t)0, (dvoid **)0);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &errhp, OCI_HTYPE_ERROR,
                (size_t) 0, (dvoid **) 0);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &svrhp, OCI_HTYPE_SERVER,
                (size_t) 0, (dvoid **) 0);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &svchp, OCI_HTYPE_SVCCTX,
                (size_t) 0, (dvoid **) 0);
OCIServerAttach(svrhp, errhp, (text *)db, strlen(db), OCI_DEFAULT);

OCIAttrSet((dvoid *) svchp, OCI_HTYPE_SVCCTX, (dvoid *) svrhp,
                (ub4) 0, OCI_ATTR_SERVER, errhp);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &authp, OCI_HTYPE_SESSION,
                (size_t) 0, (dvoid **) 0);
OCIAttrSet((void *) authp, OCI_HTYPE_SESSION, (void *) user,
                (ub4) strlen((char *) user), OCI_ATTR_USERNAME, errhp);
OCIAttrSet((void *) authp, OCI_HTYPE_SESSION, (void *) pwd,
                (ub4) strlen((char *) pwd), OCI_ATTR_PASSWORD, errhp);
OCISessionBegin (svchp, errhp, authp, OCI_CRED_RDBMS, OCI_DEFAULT);
OCIAttrSet((void *) svchp, OCI_HTYPE_SVCCTX, (void *) authp,
                (ub4) 0, OCI_ATTR_SESSION, errhp);

OCIHandleAlloc((dvoid *) envhp, (dvoid **) &stmthp,
                OCI_HTYPE_STMT, (size_t) 0, (dvoid **) 0);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &defhp,
                OCI_HTYPE_DEFINE, (size_t) 0, (dvoid **) 0);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &prmhp,
                OCI_HTYPE_PARAM, (size_t) 0, (dvoid **) 0);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &dthp,
                OCI_HTYPE_TIMESTAMP, (size_t) 0, (dvoid **) 0);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &bndhp,
                OCI_HTYPE_BIND, (size_t) 0, (dvoid **) 0);
OCIHandleAlloc((dvoid *) envhp, (dvoid **) &res,
                OCI_HTYPE_RESULT, (size_t) 0, (dvoid **) 0);

2. Oracle连接的释放

在完成操作之后，需要释放连接，这样可以有效地释放数据库中的资源。下面是一个简单的Oracle连接释放的代码示例。

OCIHandleFree((dvoid *)stmthp, OCI_HTYPE_STMT);
OCIHandleFree((dvoid *)defhp, OCI_HTYPE_DEFINE);
OCIHandleFree((dvoid *)prmhp, OCI_HTYPE_PARAM);
OCIHandleFree((dvoid *)dthp, OCI_HTYPE_TIMESTAMP);
OCIHandleFree((dvoid *)bndhp, OCI_HTYPE_BIND);
OCIHandleFree((dvoid *)res, OCI_HTYPE_RESULT);

OCISessionEnd(svchp, errhp, authp, OCI_DEFAULT);
OCIHandleFree((dvoid *)authp, OCI_HTYPE_SESSION);
OCIServerDetach(svrhp, errhp, OCI_DEFAULT);
OCIHandleFree((dvoid *)svrhp, OCI_HTYPE_SERVER);
OCIHandleFree((dvoid *)svchp, OCI_HTYPE_SVCCTX);
OCIHandleFree((dvoid *)errhp, OCI_HTYPE_ERROR);
OCIHandleFree((dvoid *)envhp, OCI_HTYPE_ENV);

以上代码中，我们使用`OCIHandleFree`来释放掉之前申请的OCI句柄，释放掉之后，连接即被释放掉了。

总结

本文介绍了如何使用C语言实现Oracle连接的释放。在使用OCI库的时候，我们需要申请并管理句柄，以保证程序的正确性和高效性。在连接的释放过程中，需要注意释放OCI句柄，以便系统能够有效地释放数据库的资源。