Recupero delle informazioni sugli errori

In questo esempio si ottengono informazioni dalle varie interfacce di errore esposte dal provider OLE DB di SQL Server Native Client.

// DumpErrorInfo queries SQLOLEDB error interfaces, retrieving available
// status or error information.
void DumpErrorInfo
    (
    IUnknown* pObjectWithError,
    REFIID IID_InterfaceWithError
    )
    {

    // Interfaces used in the example.
    IErrorInfo*             pIErrorInfoAll          = NULL;
    IErrorInfo*             pIErrorInfoRecord       = NULL;
    IErrorRecords*          pIErrorRecords          = NULL;
    ISupportErrorInfo*      pISupportErrorInfo      = NULL;
    ISQLErrorInfo*          pISQLErrorInfo          = NULL;
    ISQLServerErrorInfo*    pISQLServerErrorInfo    = NULL;

    // Number of error records.
    ULONG                   nRecs;
    ULONG                   nRec;

    // Basic error information from GetBasicErrorInfo.
    ERRORINFO               errorinfo;

    // IErrorInfo values.
    BSTR                    bstrDescription;
    BSTR                    bstrSource;

    // ISQLErrorInfo parameters.
    BSTR                    bstrSQLSTATE;
    LONG                    lNativeError;

    // ISQLServerErrorInfo parameter pointers.
    SSERRORINFO*            pSSErrorInfo = NULL;
    OLECHAR*                pSSErrorStrings = NULL;

    // Hard-code an American English locale for the example.
    DWORD                   MYLOCALEID = 0x0409;

    // Only ask for error information if the interface supports
    // it.
   if (FAILED(pObjectWithError->QueryInterface(IID_ISupportErrorInfo,
        (void**) &pISupportErrorInfo)))
       {
        wprintf_s(L"SupportErrorErrorInfo interface not supported");
        return;
        }
   if (FAILED(pISupportErrorInfo->
        InterfaceSupportsErrorInfo(IID_InterfaceWithError)))
        {
        wprintf_s(L"InterfaceWithError interface not supported");
        return;
        }

    // Do not test the return of GetErrorInfo. It can succeed and return
    // a NULL pointer in pIErrorInfoAll. Simply test the pointer.
    GetErrorInfo(0, &pIErrorInfoAll);

    if (pIErrorInfoAll != NULL)
        {
        // Test to see if it's a valid OLE DB IErrorInfo interface 
        // exposing a list of records.
        if (SUCCEEDED(pIErrorInfoAll->QueryInterface(IID_IErrorRecords,
            (void**) &pIErrorRecords)))
            {
            pIErrorRecords->GetRecordCount(&nRecs);

            // Within each record, retrieve information from each
            // of the defined interfaces.
            for (nRec = 0; nRec < nRecs; nRec++)
                {
                // From IErrorRecords, get the HRESULT and a reference
                // to the ISQLErrorInfo interface.
                pIErrorRecords->GetBasicErrorInfo(nRec, &errorinfo);
                pIErrorRecords->GetCustomErrorObject(nRec,
                    IID_ISQLErrorInfo, (IUnknown**) &pISQLErrorInfo);

                // Display the HRESULT, then use the ISQLErrorInfo.
                wprintf_s(L"HRESULT:\t%#X\n", errorinfo.hrError);

                if (pISQLErrorInfo != NULL)
                    {
                    pISQLErrorInfo->GetSQLInfo(&bstrSQLSTATE, 
                        &lNativeError);

                    // Display the SQLSTATE and native error values.
                    wprintf_s(L"SQLSTATE:\t%s\nNative Error:\t%ld\n",
                        bstrSQLSTATE, lNativeError);
                    
                    // SysFree BSTR references.
                    SysFreeString(bstrSQLSTATE);

                    // Get the ISQLServerErrorInfo interface from
                    // ISQLErrorInfo before releasing the reference.
                    pISQLErrorInfo->QueryInterface(
                        IID_ISQLServerErrorInfo,
                        (void**) &pISQLServerErrorInfo);

                    pISQLErrorInfo->Release();
                    }

                // Test to ensure the reference is valid, then
                // get error information from ISQLServerErrorInfo.
                if (pISQLServerErrorInfo != NULL)
                    {
                    pISQLServerErrorInfo->GetErrorInfo(&pSSErrorInfo,
                        &pSSErrorStrings);

                    // ISQLServerErrorInfo::GetErrorInfo succeeds
                    // even when it has nothing to return. Test the
                    // pointers before using.
                    if (pSSErrorInfo)
                        {
                        // Display the state and severity from the
                        // returned information. The error message comes
                        // from IErrorInfo::GetDescription.
                        wprintf_s(L"Error state:\t%d\nSeverity:\t%d\n",
                                pSSErrorInfo->bState,
                                pSSErrorInfo->bClass);

                        // IMalloc::Free needed to release references
                        // on returned values. For the example, assume
                        // the g_pIMalloc pointer is valid.
                        g_pIMalloc->Free(pSSErrorStrings);
                        g_pIMalloc->Free(pSSErrorInfo);
                        }

                    pISQLServerErrorInfo->Release();
                    }

                if (SUCCEEDED(pIErrorRecords->GetErrorInfo(nRec,
                    MYLOCALEID, &pIErrorInfoRecord)))
                    {
                    // Get the source and description (error message)
                    // from the record's IErrorInfo.
                    pIErrorInfoRecord->GetSource(&bstrSource);
                    pIErrorInfoRecord->GetDescription(&bstrDescription);

                    if (bstrSource != NULL)
                        {
                        wprintf_s(L"Source:\t\t%s\n", bstrSource);
                        SysFreeString(bstrSource);
                        }
                    if (bstrDescription != NULL)
                        {
                        wprintf_s(L"Error message:\t%s\n",
                            bstrDescription);
                        SysFreeString(bstrDescription);
                        }

                    pIErrorInfoRecord->Release();
                    }
                }

            pIErrorRecords->Release();
            }
        else
            {
            // IErrorInfo is valid; get the source and
            // description to see what it is.
            pIErrorInfoAll->GetSource(&bstrSource);
            pIErrorInfoAll->GetDescription(&bstrDescription);

            if (bstrSource != NULL)
                {
                wprintf_s(L"Source:\t\t%s\n", bstrSource);
                SysFreeString(bstrSource);
                }
            if (bstrDescription != NULL)
                {
                wprintf_s(L"Error message:\t%s\n", bstrDescription);
                SysFreeString(bstrDescription);
                }
            }

        pIErrorInfoAll->Release();
        }
    else
        {
        wprintf_s(L"GetErrorInfo failed.");
        }

    pISupportErrorInfo->Release();

    return;
    }

Vedere anche

Concetti

Errori