MDAC 2.5 SDK - OLE DB Programmer's Reference
Chapter 16: Errors

Error Object Example

The code in this example illustrates the use of error objects in OLE DB error handling.

////////////////////////////////////////////////////////////////////////
// myHandleResult
//
// This function is called as part of the XCHECK_HR macro; it takes an
// HRESULT, which is returned by the method called in the XCHECK_HR
// macro, and the file and line number where the method call was made.
// If the method call failed, this function attempts to get and display
// the extended error information for the call from the IErrorInfo,
// IErrorRecords, and ISQLErrorInfo interfaces.
//
////////////////////////////////////////////////////////////////////////
HRESULT myHandleResult
   (
   HRESULT              hrReturned,
   LPCWSTR              pwszFile,
   ULONG                ulLine)
{
   HRESULT              hr;
   IErrorInfo *         pIErrorInfo               = NULL;
   IErrorRecords *      pIErrorRecords            = NULL;
   ULONG                cRecords;
   ULONG                iErr;

   // If the method called as part of the XCHECK_HR macro failed,
   // we will attempt to get extended error information for the call.
   if( FAILED(hrReturned) )
   {
      // Obtain the current error object, if any, by using the
      // Automation GetErrorInfo function, which will give
      // us back an IErrorInfo interface pointer if successful.
      hr = GetErrorInfo(0, &pIErrorInfo);

      // We've got the IErrorInfo interface pointer on the error object.
      if( SUCCEEDED(hr) && pIErrorInfo )
      {
         // OLE DB extends the Automation error model by allowing
         // error objects to support the IErrorRecords interface. This
         // interface can expose information on multiple errors.
         hr = pIErrorInfo->QueryInterface(IID_IErrorRecords, 
                                          (void**)&pIErrorRecords);
         if( SUCCEEDED(hr) )
         {
            // Get the count of error records from the object.
            CHECK_HR(hr = pIErrorRecords->GetRecordCount(&cRecords));
            
            // Loop through the set of error records, and
            // display the error information for each one.
            for( iErr = 0; iErr < cRecords; iErr++ )
            {
               myDisplayErrorRecord(hrReturned, iErr, pIErrorRecords,
                                    pwszFile, ulLine);
            }
         }
         // The object didn't support IErrorRecords. Display
         // the error information for this single error.
         else
         {
            myDisplayErrorInfo(hrReturned, pIErrorInfo, pwszFile, 
                               ulLine);
         }
      }
      // There was no error object, so just display the HRESULT to the 
      // user.
      else
      {
         wprintf(L"\nNo Error Info posted; HResult: 0x%08x\n"
            L"File: %s, Line: %d\n", hrReturned, pwszFile, ulLine);
      }
   }

CLEANUP:
   if( pIErrorInfo )
      pIErrorInfo->Release();
   if( pIErrorRecords )
      pIErrorRecords->Release();
   return hrReturned;
}