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Objetos persistidos da fonte de dados

Aplica-se a: SQL Server Banco de Dados SQL do Azure Instância Gerenciada de SQL do Azure Azure Synapse Analytics Analytics Platform System (PDW)

Baixar o driver do OLE DB

O Driver do OLE DB para SQL Server é compatível com objetos persistidos da fonte de dados com a interface IPersistFile.

Exemplos

a. Inicialização de fonte de dados persistente:

Este exemplo mostra uma função que persiste as propriedades de inicialização de uma fonte de dados definindo um servidor, um banco de dados e o uso do Modo de Autenticação do Windows para conexão. O nome do servidor e o nome do banco de dados são recebidos nos parâmetros pLocation e pDatasource da função.

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. Uso de inicialização de fonte de dados persistida:

Este exemplo usa um objeto de fonte de dados persistido com propriedades de inicialização adicionais que fornecem um logon e uma senha do SQL Server.

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);  
    }  

O método IPersistFile::Save pode ser chamado antes ou depois de chamar IDBInitialize::Initialize. A chamada do método após um retorno bem-sucedido de IDBInitialize::Initialize garante que uma especificação de fonte de dados válida seja persistida.

Consulte Também

Objetos de fonte de dados (OLE DB)