StayInSync, propriété – Exemple (VC++)

S’applique à : Access 2013, Office 2013

Cet exemple montre comment la propriété StayInSync facilite l'accès aux lignes d'un objet Recordset hiérarchique.

La boucle externe affiche le nom et le prénom, l'état et l'identification de chaque auteur. Le Recordset ajouté pour chaque ligne est extrait de la collection Fields et automatiquement attribué à rstTitleAuthor par la propriété StayInSync chaque fois que le parent Recordset change de ligne. La boucle interne affiche quatre champs de chaque ligne dans le jeu d’enregistrements ajouté.

 
// BeginStayInSyncCpp 
#import "C:\Program Files\Common Files\System\ADO\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); 
void PrintProviderError(_ConnectionPtr pConnection); 
void PrintComError(_com_error &e); 
 
////////////////////////////////////////////////////////// 
// // 
// Main Function // 
// // 
////////////////////////////////////////////////////////// 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 StayInSyncX(); 
 
 ::CoUninitialize(); 
} 
 
////////////////////////////////////////////////////////// 
// // 
// StayInSyncX Function // 
// // 
////////////////////////////////////////////////////////// 
void StayInSyncX(void) 
{ 
 HRESULT hr = S_OK; 
 
 // Define string variables. 
 _bstr_t strCnn("Provider='MSDataShape';" 
 "Data Provider='sqloledb';Data Source='MySqlServer';" 
 "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; 
 int intLineCnt=0; 
 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); 
 intLineCnt++; 
 
 if (intLineCnt%15 == 0) 
 { 
 printf("\nPress any key to continue...\n"); 
 getch(); 
 } 
 
 _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); 
 intLineCnt++; 
 
 if (intLineCnt%15 == 0) 
 { 
 printf("\nPress any key to continue...\n"); 
 getch(); 
 } 
 pRstTitleAuthor->MoveNext(); 
 } 
 pRst->MoveNext(); 
 } 
 } 
 catch(_com_error &e) 
 { 
 // Notify the user of errors if any. 
 // Pass a 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(); 
} 
 
////////////////////////////////////////////////////////// 
// // 
// PrintProviderError Function // 
// // 
////////////////////////////////////////////////////////// 
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); 
 } 
 } 
} 
 
////////////////////////////////////////////////////////// 
// // 
// PrintComError Function // 
// // 
////////////////////////////////////////////////////////// 
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); 
 
} 
// EndStayInSyncCpp