MoveFirst, MoveLast, MoveNext et MovePrevious, méthodes – Exemple (VC++)

S’applique à : Access 2013, Office 2013

Cet exemple utilise les méthodes MoveFirst, MoveLast, MoveNext et MovePrevious pour déplacer le pointeur d’un enregistrement d’un objet Recordset selon la commande fournie. La fonction MoveAny est nécessaire à l'exécution de cet exemple.

 
// BeginMoveFirstCpp 
#include <ole2.h> 
#include <stdio.h> 
 
#import "c:\Program Files\Common Files\System\ADO\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); 
 
///////////////////////////////// 
// Main Function // 
///////////////////////////////// 
 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 MoveFirstX(); 
 
 ::CoUninitialize(); 
} 
 
////////////////////////////////////// 
// MoveFirstX Function // 
////////////////////////////////////// 
 
void MoveFirstX() 
{ 
 HRESULT hr = S_OK; 
 _RecordsetPtr pRstAuthors = NULL; 
 _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';" 
 "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("%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(); 
} 
 
///////////////////////////////// 
// MoveAny Function // 
///////////////////////////////// 
 
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; 
 } 
 } 
} 
 
//////////////////////////////////////////// 
// 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("\t Error number: %x\t%s", pErr->Number, 
 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); 
} 
// EndMoveFirstCpp