Ejemplo de las propiedades AbsolutePosition y CursorLocation (VC++)

Se aplica a: Access 2013, Office 2013

En este ejemplo se muestra cómo la propiedad AbsolutePosition puede realizar un seguimiento del progreso de un bucle que enumera todos los registros de un objeto Recordset. Usa la propiedad CursorLocation para habilitar la propiedad AbsolutePosition estableciendo el cursor en un cursor de cliente.

 
// BeginAbsolutePositionCpp 
#import "C:\Program Files\Common Files\System\ADO\msado15.dll" no_namespace rename("EOF", "EndOfFile") 
 
#include <ole2.h> 
#include <stdio.h> 
#include "conio.h" 
#include "AbsolutePositionX.h" 
 
//Function Declarations 
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);}; 
void AbsolutePositionX(void); 
void AbsolutePosition2X(void); 
void PrintProviderError(_ConnectionPtr pConnection); 
 
/////////////////////////////////////////////////////////// 
// // 
// Main Function // 
// // 
/////////////////////////////////////////////////////////// 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 AbsolutePositionX(); 
 
 
 //Clear the screen for the next display 
 printf("Press any key to continue..."); 
 getch(); 
 system("cls"); 
 
 AbsolutePosition2X(); 
 
 ::CoUninitialize(); 
} 
 
/////////////////////////////////////////////////////////// 
// // 
// AbsolutePositionX Function // 
// // 
/////////////////////////////////////////////////////////// 
 
void AbsolutePositionX(void) 
{ 
 HRESULT hr = S_OK; 
 
 // Define ADO object pointers. 
 // Initialize pointers on define. 
 // These are in the ADODB:: namespace. 
 _RecordsetPtr pRstEmployees = NULL; 
 
 //Define Other Variables 
 //Interface Pointer declared.(VC++ Extensions) 
 IADORecordBinding *picRs = NULL; 
 CEmployeeRs emprs; //C++ class object 
 _bstr_t strMessage; 
 char chKey; 
 
 //Open a recordset using a Client Cursor 
 //For the Employee Table 
 
 _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';" 
 "Initial Catalog='pubs';Integrated Security='SSPI';"); 
 
 try 
 { 
 //Open a recordset. 
 TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset))); 
 
 //Use client cursor to enable Absoluteposition property. 
 pRstEmployees->CursorLocation = adUseClient; 
 
 //You have to explicitly pass the default Cursor type 
 //and LockType to the Recordset. 
 TESTHR( pRstEmployees->Open("employee", 
 strCnn,adOpenForwardOnly,adLockReadOnly,adCmdTable)); 
 
 // Open an IADORecordBinding interface pointer which we'll use 
 // for Binding Recordset to a class. 
 TESTHR(pRstEmployees->QueryInterface( 
 __uuidof(IADORecordBinding),(LPVOID*)&picRs)); 
 
 //Bind the Recordset to a C++ Class here 
 TESTHR(picRs->BindToRecordset(&emprs)); 
 
 strMessage= ""; 
 
 //Enumerate recordset 
 do 
 { 
 //Display Current Record Information 
 printf("Employee : %s \n record %ld of %d", 
 emprs.lau_lnameStatus == adFldOK ? 
 emprs.m_szau_lname : "<NULL>", 
 pRstEmployees->AbsolutePosition, 
 pRstEmployees->RecordCount); 
 
 printf("\nContinue?(y/n) :"); 
 
 do 
 { 
 chKey = getch(); 
 }while(chKey != 'y' && chKey !='n'); 
 
 //Clear the Screen for the next output 
 system("cls"); 
 
 if(chKey == 'n') 
 break; 
 
 strMessage = ""; 
 pRstEmployees->MoveNext(); 
 }while(!(pRstEmployees->EndOfFile)); 
 } 
 catch(_com_error &e) 
 { 
 // Notify the user of errors if any. 
 _variant_t vtConnect = pRstEmployees->GetActiveConnection(); 
 
 // GetActiveConnection returns connect string if connection 
 // is not open, else returns Connection object. 
 switch(vtConnect.vt) 
 { 
 case VT_BSTR: 
 printf("Error:\n"); 
 printf("Code = %08lx\n", e.Error()); 
 printf("Message = %s\n", e.ErrorMessage()); 
 printf("Source = %s\n", (LPCSTR) e.Source()); 
 printf("Description = %s\n", (LPCSTR) e.Description()); 
 break; 
 case VT_DISPATCH: 
 PrintProviderError(vtConnect); 
 break; 
 default: 
 printf("Errors occured."); 
 break; 
 } 
 } 
 
 // Clean up objects before exit. 
 //Release the IADORecordset Interface here 
 if (picRs) 
 picRs->Release(); 
 
 if (pRstEmployees) 
 if (pRstEmployees->State == adStateOpen) 
 pRstEmployees->Close(); 
} 
 
 
/////////////////////////////////////////////////////////// 
// // 
// AbsolutePosition2X Function // 
// // 
/////////////////////////////////////////////////////////// 
 
void AbsolutePosition2X(void) 
{ 
 HRESULT hr = S_OK; 
 
 // Define ADO object pointers. 
 // Initialize pointers on define. 
 // These are in the ADODB:: namespace. 
 _RecordsetPtr pRstEmployees = NULL; 
 
 //Define Other Variables 
 //Interface Pointer declared.(VC++ Extensions) 
 IADORecordBinding *picRs = NULL; 
 CEmployeeRs emprs; //C++ class object 
 _bstr_t strMessage; 
 
 //Open a recordset using a Client Cursor 
 //For the Employee Table 
 
 _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';" 
 "Initial Catalog='pubs';Integrated Security='SSPI';"); 
 
 try 
 { 
 //Open a recordset. 
 TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset))); 
 
 //Use client cursor to enable Absoluteposition property. 
 pRstEmployees->CursorLocation = adUseClient; 
 
 //You have to explicitly pass the default Cursor type 
 //and LockType to the Recordset. 
 TESTHR(pRstEmployees->Open("employee", 
 strCnn,adOpenStatic,adLockReadOnly,adCmdTable)); 
 
 // Open an IADORecordBinding interface pointer which we'll use 
 // for Binding Recordset to a class. 
 TESTHR(pRstEmployees->QueryInterface( 
 __uuidof(IADORecordBinding),(LPVOID*)&picRs)); 
 
 //Bind the Recordset to a C++ Class here 
 TESTHR(picRs->BindToRecordset(&emprs)); 
 
 long lGoToPos = 21; 
 
 pRstEmployees->AbsolutePosition = (PositionEnum)lGoToPos; 
 
 //Display Current Record Information 
 printf("Employee : %s \n record %ld of %d", 
 emprs.lau_lnameStatus == adFldOK ? emprs.m_szau_lname : "<NULL>", pRstEmployees->AbsolutePosition, 
 pRstEmployees->RecordCount); 
 
 printf("\nPress any key to continue:"); 
 getch(); 
 } 
 catch(_com_error &e) 
 { 
 // Notify the user of errors if any. 
 _variant_t vtConnect = pRstEmployees->GetActiveConnection(); 
 
 // GetActiveConnection returns connect string if connection 
 // is not open, else returns Connection object. 
 switch(vtConnect.vt) 
 { 
 case VT_BSTR: 
 printf("Error:\n"); 
 printf("Code = %08lx\n", e.Error()); 
 printf("Message = %s\n", e.ErrorMessage()); 
 printf("Source = %s\n", (LPCSTR) e.Source()); 
 printf("Description = %s\n", (LPCSTR) e.Description()); 
 break; 
 case VT_DISPATCH: 
 PrintProviderError(vtConnect); 
 break; 
 default: 
 printf("Errors occured."); 
 break; 
 } 
 } 
 
 // Clean up objects before exit. 
 //Release the IADORecordset Interface here 
 if (picRs) 
 picRs->Release(); 
 
 if (pRstEmployees) 
 if (pRstEmployees->State == adStateOpen) 
 pRstEmployees->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; 
 long nCount = 0; 
 long i = 0; 
 
 if( (pConnection->Errors->Count) > 0) 
 { 
 nCount = pConnection->Errors->Count; 
 // Collection ranges from 0 to nCount -1. 
 for(i = 0; i < nCount; i++) 
 { 
 pErr = pConnection->Errors->GetItem(i); 
 printf("\t Error number: %x\t%s", 
 pErr->Number,(LPCSTR) pErr->Description); 
 } 
 } 
} 
 
// EndAbsolutePositionCpp 

AbsolutePositionX.h

 
// BeginAbsolutePositionH 
#include <ole2.h> 
#include <stdio.h> 
#include "icrsint.h" 
 
 
//This Class extracts lastname. 
 
class CEmployeeRs : public CADORecordBinding 
{ 
BEGIN_ADO_BINDING(CEmployeeRs) 
 
 //Column lname is the 4th field in the recordset 
 
 ADO_VARIABLE_LENGTH_ENTRY2(4, adVarChar, m_szau_lname, 
 sizeof(m_szau_lname), lau_lnameStatus, TRUE) 
 
END_ADO_BINDING() 
 
public: 
 CHAR m_szau_lname[41]; 
 ULONG lau_lnameStatus; 
 
}; 
// EndAbsolutePositionH