StayInSync Property Example (VC++)

This example demonstrates how the StayInSync property facilitates accessing rows in a hierarchical Recordset.

The outer loop displays each author's first and last name, state, and identification. The appended Recordset for each row is retrieved from the Fields collection and automatically assigned to rstTitleAuthor by the StayInSync property whenever the parent Recordset moves to a new row. The inner loop displays four fields from each row in the appended recordset.

// BeginStayInSyncCpp.cpp  
// compile with: /EHsc  
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")  
  
#include <ole2.h>  
#include <stdio.h>  
#include <conio.h>  
  
// Function declarations  
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };  
void StayInSyncX();  
void PrintProviderError(_ConnectionPtr pConnection);  
void PrintComError(_com_error &e);  
  
int main() {  
   if ( FAILED(::CoInitialize(NULL)) )  
      return -1 ;  
  
   StayInSyncX();  
   ::CoUninitialize();  
}  
  
void StayInSyncX() {  
   HRESULT  hr = S_OK;  
  
   // Define string variables.  
   _bstr_t strCnn("Provider='MSDataShape'; Data Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");  
  
   // Define ADO object pointers.  Initialize pointers on define.  
   // These are in the ADODB::  namespace.  
   _ConnectionPtr pConnection = NULL;  
   _RecordsetPtr pRst = NULL;  
   _RecordsetPtr pRstTitleAuthor = NULL;  
  
   try {  
      TESTHR(pRstTitleAuthor.CreateInstance(__uuidof(Recordset)));  
      TESTHR(pConnection.CreateInstance(__uuidof(Connection)));  
      TESTHR(pRst.CreateInstance(__uuidof(Recordset)));  
  
      // Open connection.  
      pConnection->Open (strCnn, "", "", adConnectUnspecified);  
      pRst->PutStayInSync(true);  
  
      // Open recordset with names from Author & titleauthor table.  
      pRst->Open("SHAPE  {select * from authors} "   
         "APPEND ({select * from titleauthor}"  
         "RELATE au_id TO au_id) AS chapTitleAuthor",  
         _variant_t((IDispatch*)pConnection, true), adOpenStatic, adLockReadOnly, adCmdText);  
  
      pRstTitleAuthor = pRst->GetFields()->GetItem("chapTitleAuthor")->Value;  
      while (!(pRst->EndOfFile)) {      
         printf("\n%s  %s  %s    %s\n", (LPCSTR)(_bstr_t)pRst->  
            Fields->GetItem("au_fname")->Value,  
            (LPCSTR)(_bstr_t)pRst->Fields->GetItem("au_lname")->Value,  
            (LPCSTR)(_bstr_t)pRst->Fields->GetItem("state")->Value,   
            (LPCSTR)(_bstr_t)pRst->Fields->GetItem("au_id")->Value);  
  
         _variant_t vIndex;  
         while ( !(pRstTitleAuthor->EndOfFile) ) {  
            vIndex = (short) 0;  
            printf("%s    ",(LPCSTR)(_bstr_t)pRstTitleAuthor->Fields->Item[&vIndex]->Value);  
            vIndex = (short) 1;  
            printf("%s    ",(LPCSTR)(_bstr_t)pRstTitleAuthor->Fields->Item[&vIndex]->Value);  
            vIndex = (short) 2;  
            printf("%s    ",(LPCSTR)(_bstr_t)pRstTitleAuthor->Fields->Item[&vIndex]->Value);  
            vIndex = (short) 3;  
            printf("%s\n",(LPCSTR)(_bstr_t)pRstTitleAuthor->Fields->Item[&vIndex]->Value);  
  
            pRstTitleAuthor->MoveNext();  
         }  
         pRst->MoveNext();  
      }  
   }  
   catch(_com_error &e) {  
      // Notify user of errors, if any.  Pass connection pointer accessed from the Recordset.  
      PrintProviderError(pConnection);  
      PrintComError(e);     
   }  
  
   // Clean up objects before exit.  
   if (pRst)  
      if (pRst->State == adStateOpen)  
         pRst->Close();  
   if (pConnection)  
      if (pConnection->State == adStateOpen)  
         pConnection->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("Error number: %x\t%s\n", 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);  
}  

See Also

Fields Collection (ADO)
Recordset Object (ADO)
StayInSync Property