持久化数据源对象

SQL Server Native Client OLE DB 提供程序支持具有 IPersistFile 接口的持久化数据源对象。

示例

A. 使数据源初始化持久化：

此示例显示使数据源初始化属性持久化的一个函数，它为连接定义服务器、数据库并使用 Windows 身份验证模式。 在函数的 pLocation 和 pDatasource 参数中接收服务器名称和数据库名称 。

HRESULT SetAndSaveInitProps  
    (  
    IDBInitialize* pIDBInitialize,  
    WCHAR* pDataSource,  
    WCHAR* pCatalog,  
    BOOL bUseWinNTAuth  
    )  
    {  
    const ULONG     nProps = 4;  
    ULONG           nSSProps;  
    ULONG           nPropSets;  
    ULONG           nProp;  
    IDBProperties*  pIDBProperties  = NULL;  
    IPersistFile*   pIPersistFile   = NULL;  
    DBPROP          aInitProps[nProps];  
    DBPROP*         aSSInitProps    = NULL;  
    DBPROPSET*      aInitPropSets   = NULL;  
    HRESULT         hr;  
  
        nSSProps = 0;  
        nPropSets = 1;  
  
    aInitPropSets = new DBPROPSET[nPropSets];  
  
    // Initialize common property options.  
    for (nProp = 0; nProp < nProps; nProp++)  
        {  
        VariantInit(&aInitProps[nProp].vValue);  
        aInitProps[nProp].dwOptions = DBPROPOPTIONS_REQUIRED;  
        aInitProps[nProp].colid = DB_NULLID;  
        }  
  
    // Level of prompting that will be done to complete the connection  
    // process.  
    aInitProps[0].dwPropertyID = DBPROP_INIT_PROMPT;  
    aInitProps[0].vValue.vt = VT_I2;  
    aInitProps[0].vValue.iVal = DBPROMPT_NOPROMPT;       
  
    // Server name.  
    aInitProps[1].dwPropertyID = DBPROP_INIT_DATASOURCE;      
    aInitProps[1].vValue.vt = VT_BSTR;  
    aInitProps[1].vValue.bstrVal = SysAllocString(pDataSource);  
  
    // Database.  
    aInitProps[2].dwPropertyID = DBPROP_INIT_CATALOG;  
    aInitProps[2].vValue.vt = VT_BSTR;  
    aInitProps[2].vValue.bstrVal = SysAllocString(pCatalog);  
  
    aInitProps[3].dwPropertyID = DBPROP_AUTH_INTEGRATED;  
    if (bUseWinNTAuth == TRUE)  
    {  
        aInitProps[3].vValue.vt = VT_BSTR;  
        aInitProps[3].vValue.bstrVal = SysAllocString(L"SSPI");  
    } //end if  
  
    // Now that properties are set, construct the PropertySet array.  
    aInitPropSets[0].guidPropertySet = DBPROPSET_DBINIT;  
    aInitPropSets[0].cProperties = nProps;  
    aInitPropSets[0].rgProperties = aInitProps;  
  
    // Set initialization properties  
    pIDBInitialize->QueryInterface(IID_IDBProperties,  
        (void**) &pIDBProperties);  
    hr = pIDBProperties->SetProperties(nPropSets, aInitPropSets);  
    if (FAILED(hr))  
        {  
        // Display error from failed SetProperties.  
        }  
    pIDBProperties->Release();  
  
    // Free references on OLE known strings.  
    for (nProp = 0; nProp < nProps; nProp++)  
        {  
        if (aInitProps[nProp].vValue.vt == VT_BSTR)  
            SysFreeString(aInitProps[nProp].vValue.bstrVal);  
        }  
  
    for (nProp = 0; nProp < nSSProps; nProp++)  
        {  
        if (aSSInitProps[nProp].vValue.vt == VT_BSTR)  
            SysFreeString(aSSInitProps[nProp].vValue.bstrVal);  
        }  
  
    // Free dynamically allocated memory.  
    delete [] aInitPropSets;  
    delete [] aSSInitProps;  
  
    // On success, persist the data source.  
    if (SUCCEEDED(hr))  
        {  
        pIDBInitialize->QueryInterface(IID_IPersistFile,  
            (void**) &pIPersistFile);  
  
        hr = pIPersistFile->Save(OLESTR("MyDataSource.txt"), FALSE);  
  
        if (FAILED(hr))  
            {  
            // Display errors from IPersistFile interface.  
            }  
        pIPersistFile->Release();  
        }  
  
    return (hr);  
    }  

B. 使用持久化的数据源初始化：

此示例使用具有其他初始化属性的一个持久化数据源对象，这些属性提供 SQL Server 登录名和密码。

HRESULT InitFromPersistedDS  
    (  
    IDBInitialize* pIDBInitialize,  
    WCHAR* pPersistedDSN,  
    WCHAR* pUID,  
    WCHAR* pPWD  
    )  
    {  
    //const ULONG   nProps = 3;  
    const ULONG     nProps = 1;  
    const ULONG     nPropSets = 1;  
    ULONG           nProp;  
    IDBProperties*  pIDBProperties  = NULL;  
    IPersistFile*   pIPersistFile   = NULL;  
    DBPROP          aInitProps[nProps];  
    DBPROPSET       aInitPropSets[nPropSets];  
    HRESULT         hr;  
  
    // First load the persisted data source information.  
    pIDBInitialize->QueryInterface(IID_IPersistFile,  
        (void**) &pIPersistFile);  
  
    hr = pIPersistFile->Load(pPersistedDSN, STGM_DIRECT);  
  
    if (FAILED(hr))  
        {  
        // Display errors from IPersistFile interface.  
        }  
    pIPersistFile->Release();  
  
    if (FAILED(hr))  
        {  
        return (hr);  
        }  
  
    // Initialize common property options.  
    for (nProp = 0; nProp < nProps; nProp++)  
        {  
        VariantInit(&aInitProps[nProp].vValue);  
        aInitProps[nProp].dwOptions = DBPROPOPTIONS_REQUIRED;  
        aInitProps[nProp].colid = DB_NULLID;  
        }  
  
    // Level of prompting that will be done to complete the connection  
    // process.  
    aInitProps[0].dwPropertyID = DBPROP_INIT_PROMPT;  
    aInitProps[0].vValue.vt = VT_I2;  
    aInitProps[0].vValue.iVal = DBPROMPT_NOPROMPT;      
  
    // Now that properties are set, construct the PropertySet array.  
    aInitPropSets[0].guidPropertySet = DBPROPSET_DBINIT;  
    aInitPropSets[0].cProperties = nProps;  
    aInitPropSets[0].rgProperties = aInitProps;  
  
    // Set initialization properties  
    pIDBInitialize->QueryInterface(IID_IDBProperties,  
        (void**) &pIDBProperties);  
    hr = pIDBProperties->SetProperties(nPropSets, aInitPropSets);  
    if (SUCCEEDED(hr))  
        {  
        hr = pIDBInitialize->Initialize();  
        if (FAILED(hr))  
            {  
            DumpError(pIDBInitialize, IID_IDBInitialize);  
            }  
        }  
    else  
        {  
        // Display error from failed SetProperties.  
        }  
    pIDBProperties->Release();  
  
    // Free references on OLE known strings.  
    for (nProp = 0; nProp < nProps; nProp++)  
        {  
        if (aInitProps[nProp].vValue.vt == VT_BSTR)  
            SysFreeString(aInitProps[nProp].vValue.bstrVal);  
        }  
  
    return (hr);  
    }  

可在调用 IDBInitialize::Initialize 前后调用 IPersistFile::Save 方法 。 如果在从 IDBInitialize::Initialize 成功返回后调用该方法，可确保使有效的数据源指定持久化 。

另请参阅

数据源对象 (OLE DB)