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NextRecordset Method Example (VC++)

This example uses the NextRecordset method to view the data in a recordset that uses a compound command statement made up of three separate SELECT statements.

// BeginNextRecordsetCpp.cpp
// compile with: /EHsc
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")

#include <stdio.h>
#include <ole2.h>
#include <conio.h>
#include <stdlib.h>

//Function Declaration.
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void NextRecordsetX();
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

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

   NextRecordsetX();
   ::CoUninitialize();
}

void NextRecordsetX() {
   // Define ADO object pointers.  Initialize pointers on define.  These are in the ADODB::  namespace.
   _RecordsetPtr pRstCompound = NULL;

   // Define Other Variables
   _variant_t index;
   index.vt = VT_I2;

   // Assign connection string to a variable.
   _bstr_t strCnn("Provider='sqloledb';Data Source='(local)';Initial Catalog='pubs';Integrated Security='SSPI';");

   try {
      // Open recordset from Authors table.
      TESTHR(pRstCompound.CreateInstance(__uuidof(Recordset)));

      // Pass the Cursor type and Lock type to the Recordset.
      pRstCompound->Open("SELECT * FROM authors; SELECT * FROM stores;SELECT * FROM jobs", 
         strCnn, adOpenForwardOnly, adLockReadOnly, adCmdText);

      // Display results from each SELECT statement.
      int intCount = 1;
      while (!(pRstCompound == NULL)) {
         printf("\n\nContents of recordset #%d\n", intCount);

         while (!pRstCompound->EndOfFile) {
            index.iVal = 0;
            printf("%s\t", (LPCSTR)(_bstr_t)pRstCompound->GetFields()->GetItem(& index)->Value);
            index.iVal = 1;
            printf("%s\n", (LPCSTR)(_bstr_t)pRstCompound->Fields->GetItem(& index)->Value);

            pRstCompound->MoveNext();

         }
         long lngRec = 0;
         pRstCompound = pRstCompound->NextRecordset((VARIANT *)lngRec);

         intCount = intCount + 1;
      }
   }
   catch(_com_error &e) {
      // Notify the user of errors if any.  Pass a connection pointer accessed from the Recordset.
      _variant_t vtConnect = pRstCompound->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 (pRstCompound)
      if (pRstCompound->State == adStateOpen)
         pRstCompound->Close();
}

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, (LPCSTR) 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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