MDAC 2.5 SDK - OLE DB Providers
OLE DB Provider for SQL Server

SQLOLEDB Example: Retrieving Error Information

The following example obtains information from the various error interfaces exposed by SQLOLEDB.

// 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;

      // Request error information only 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 whether 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, and 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, and 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;
}