Ejemplo de las propiedades Provider y DefaultDatabase (VC++)

Se aplica a: Access 2013, Office 2013

En este ejemplo se muestra la propiedad Provider al abrir tres objetos Connection mediante diferentes proveedores. También se utiliza la propiedad DefaultDatabase para establecer la base de datos predeterminada del Proveedor Microsoft ODBC.

 
// BeginProviderCpp 
#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 ProviderX(void); 
void PrintProviderError(_ConnectionPtr pConnection); 
void PrintComError(_com_error &e); 
 
/////////////////////////////// 
// // 
// Main Function // 
// // 
/////////////////////////////// 
void main() 
{ 
 if(FAILED(::CoInitialize(NULL))) 
 return; 
 
 ProviderX(); 
 
 ::CoUninitialize(); 
} 
 
///////////////////////////////// 
// // 
// ProviderX Function // 
// // 
///////////////////////////////// 
 
void ProviderX(void) 
{ 
 HRESULT hr = S_OK; 
 
 // Define ADO object pointers. 
 // Initialize pointers on define. 
 // These are in the ADODB:: namespace. 
 _ConnectionPtr pConnection1 = NULL; 
 _ConnectionPtr pConnection2 = NULL; 
 _ConnectionPtr pConnection3 = NULL; 
 
 try 
 { 
 // Open a Connection using the Microsoft ODBC provider. 
 TESTHR(pConnection1.CreateInstance(__uuidof(Connection))); 
 pConnection1->ConnectionString = "driver={SQL Server};" 
 "server='MySqlServer';user id='MyUserId';password='MyPassword';"; 
 pConnection1->Open("","","",adConnectUnspecified); 
 pConnection1->DefaultDatabase = "pubs"; 
 
 // Display the provider 
 printf("\n\nConnection1 provider: %s \n\n", 
 (LPCSTR)pConnection1->Provider); 
 
 // Open a connection using the OLE DB Provider for Microsoft Jet. 
 TESTHR(pConnection2.CreateInstance(__uuidof(Connection))); 
 pConnection2->Provider = "Microsoft.Jet.OLEDB.4.0"; 
 
 char *sConn = "c:\\Program Files\\Microsoft Office\\Office\\" 
 "Samples\\Northwind.mdb"; 
 
 pConnection2->Open(sConn,"admin","",NULL); 
 
 // Display the provider 
 printf("Connection2 provider: %s \n\n",(LPCSTR)pConnection2-> 
 Provider); 
 
 // Open a Connection using the Microsoft SQL Server provider. 
 TESTHR(pConnection3.CreateInstance(__uuidof(Connection))); 
 pConnection3->Provider = "sqloledb"; 
 pConnection3->Open("Data Source='MySqlServer';Initial Catalog='pubs';", 
 "MyUserId","MyPassword",NULL); 
 
 // Display the provider. 
 printf("Connection3 provider: %s\n\n",(LPCSTR)pConnection3-> 
 Provider); 
 } 
 
 catch (_com_error &e) 
 { 
 // Notify the user of errors if any. 
 PrintProviderError(pConnection1); 
 if(pConnection2) PrintProviderError(pConnection2); 
 if(pConnection3) PrintProviderError(pConnection3); 
 PrintComError(e); 
 } 
 
 if (pConnection1) 
 if (pConnection1->State == adStateOpen) 
 pConnection1->Close(); 
 if (pConnection2) 
 if (pConnection2->State == adStateOpen) 
 pConnection2->Close(); 
 if (pConnection3) 
 if (pConnection3->State == adStateOpen) 
 pConnection3->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); 
} 
// EndProviderCpp