Retrieving Error Information
This example obtains information from the various error interfaces exposed by the SQL Native Client OLE DB provider.
// 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(L"SupportErrorErrorInfo interface not supported");
return;
}
if (FAILED(pISupportErrorInfo->
InterfaceSupportsErrorInfo(IID_InterfaceWithError)))
{
wprintf(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(L"HRESULT:\t%#X\n", errorinfo.hrError);
if (pISQLErrorInfo != NULL)
{
pISQLErrorInfo->GetSQLInfo(&bstrSQLSTATE,
&lNativeError);
// Display the SQLSTATE and native error values.
wprintf(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(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(L"Source:\t\t%s\n", bstrSource);
SysFreeString(bstrSource);
}
if (bstrDescription != NULL)
{
wprintf(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(L"Source:\t\t%s\n", bstrSource);
SysFreeString(bstrSource);
}
if (bstrDescription != NULL)
{
wprintf(L"Error message:\t%s\n", bstrDescription);
SysFreeString(bstrDescription);
}
}
pIErrorInfoAll->Release();
}
else
{
wprintf(L"GetErrorInfo failed.");
}
pISupportErrorInfo->Release();
return;
}