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MoveFirst, MoveLast, MoveNext, and MovePrevious Methods Example (VC++)

This example uses the MoveFirst, MoveLast, MoveNext, and MovePrevious methods to move the record pointer of a Recordset based on the supplied command. The MoveAny function is required for this example to run.

// MoveFirstMoveLastMoveNextSample.cpp
// compile with: /EHsc
#include <ole2.h>
#include <stdio.h>

#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")

// Function declarations
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };
void MoveFirstX();
void MoveAny(int intChoice, _RecordsetPtr pRstTemp);
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

int main() {
   if ( FAILED(::CoInitialize(NULL)) )
      return -1;

   MoveFirstX();
   ::CoUninitialize();
}

void MoveFirstX() {
   HRESULT hr = S_OK;
   _RecordsetPtr pRstAuthors = NULL;
   _bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");
   _bstr_t strMessage("UPDATE Titles SET Type = "
      "'psychology' WHERE Type = 'self_help'");
   int intCommand = 0;

   // Temporary string variable for type conversion for printing.
   _bstr_t  bstrFName;
   _bstr_t  bstrLName;

   try {
      // Open recordset from Authors table.
      TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset)));
      pRstAuthors->CursorType = adOpenStatic;

      // Use client cursor to enable AbsolutePosition property.
      pRstAuthors->CursorLocation = adUseClient;
      pRstAuthors->Open("Authors", strCnn, adOpenStatic, adLockBatchOptimistic, adCmdTable);

      // Show current record information and get user's method choice.
      while (true) {   // Continuous loop.
         // Convert variant string to convertable string type.
         bstrFName = pRstAuthors->Fields->Item["au_fName"]->Value;
         bstrLName = pRstAuthors->Fields->Item["au_lName"]->Value;

         printf("Name: %s %s\n Record %d of %d\n\n",
            (LPCSTR) bstrFName,
            (LPCSTR) bstrLName,
            pRstAuthors->AbsolutePosition,
            pRstAuthors->RecordCount);
         printf("[1 - MoveFirst, 2 - MoveLast, \n");
         printf(" 3 - MoveNext, 4 - MovePrevious, 5 - Quit]\n");

         scanf_s("%d", &intCommand);

         if ((intCommand < 1) || (intCommand > 4))
            break;   // Out of range entry exits program loop.

         // Call method based on user's input.
         MoveAny(intCommand, pRstAuthors);
      }
   }
   catch (_com_error &e) {
      // Notify the user of errors if any.
      // Pass a connection pointer accessed from the Recordset.
      _variant_t vtConnect = pRstAuthors->GetActiveConnection();

      // GetActiveConnection returns connect string if connection
      // is not open, else returns Connection object.
      switch(vtConnect.vt) {
         case VT_BSTR:
            PrintComError(e);
            break;
         case VT_DISPATCH:
            PrintProviderError(vtConnect);
            break;
         default:
            printf("Errors occured.");
            break;
      }
   }

   // Clean up objects before exit.
   if (pRstAuthors)
      if (pRstAuthors->State == adStateOpen)
         pRstAuthors->Close();
}

void MoveAny(int intChoice, _RecordsetPtr pRstTemp) {
   // Use specified method, trapping for BOF and EOF
   try {
      switch(intChoice) {
         case 1:
            pRstTemp->MoveFirst();
            break;
         case 2:
            pRstTemp->MoveLast();
            break;
         case 3:
            pRstTemp->MoveNext();
            if (pRstTemp->EndOfFile) {
               printf("\nAlready at end of recordset!\n");
               pRstTemp->MoveLast();
            }    // End If
            break;
         case 4:
            pRstTemp->MovePrevious();
            if (pRstTemp->BOF) {
               printf("\nAlready at beginning of recordset!\n");
               pRstTemp->MoveFirst();
            }
            break;
         default:
            ;
      }
   }

   catch(_com_error &e) {
      // Notify the user of errors if any.
      // Pass a connection pointer accessed from the Recordset.
      _variant_t vtConnect = pRstTemp->GetActiveConnection();

      // GetActiveConnection returns connect string if connection
      // is not open, else returns Connection object.
      switch(vtConnect.vt)  {
         case VT_BSTR:
            PrintComError(e);
            break;
         case VT_DISPATCH:
            PrintProviderError(vtConnect);
            break;
         default:
            printf("Errors occured.");
            break;
      }
   }
}

void PrintProviderError(_ConnectionPtr pConnection) {
   // Print Provider Errors from Connection object.

   // pErr is a record object in the Connection's Error collection.
   ErrorPtr pErr = NULL;

   if ( (pConnection->Errors->Count) > 0) {
      long nCount = pConnection->Errors->Count;
      // Collection ranges from 0 to nCount - 1.
      for ( long i = 0 ; i < nCount ; i++) {
         pErr = pConnection->Errors->GetItem(i);
         printf("\t Error number: %x\t%s", pErr->Number, pErr->Description);
      }
   }
}

void PrintComError(_com_error &e) {
   _bstr_t bstrSource(e.Source());
   _bstr_t bstrDescription(e.Description());

   // Print Com errors.
   printf("Error\n");
   printf("\tCode = %08lx\n", e.Error());
   printf("\tCode meaning = %s\n", e.ErrorMessage());
   printf("\tSource = %s\n", (LPCSTR) bstrSource);
   printf("\tDescription = %s\n", (LPCSTR) bstrDescription);
}

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