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

En este ejemplo se muestra la propiedad Provider al abrir tres objetos Connection mediante distintos proveedores. También usa la propiedad DefaultDatabase para establecer la base de datos predeterminada para el proveedor ODBC de Microsoft.

// Provider_and_DefaultDatabase_Properties.cpp  
// compile with: /EHsc  
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")  
  
// Function declarations  
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};  
void ProviderX();  
void PrintProviderError(_ConnectionPtr pConnection);  
void PrintComError(_com_error &e);  
  
int main() {  
   if (FAILED(::CoInitialize(NULL)))  
      return -1;  
  
   ProviderX();  
   ::CoUninitialize();  
}  
  
void ProviderX() {  
   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 = "DSN=Data;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:\\Northwind.mdb";  
      pConnection2->Open(sConn, "admin", "", NULL);  
      // Display the provider  
      printf("Connection2 provider: %s \n\n",(LPCSTR)pConnection2->Provider);  
  
      // Requires SQL Server authentication  
      // Open a Connection using the Microsoft SQL Server provider.  
      TESTHR(pConnection3.CreateInstance(__uuidof(Connection)));  
      pConnection3->Provider = "sqloledb";  
      pConnection3->Open("Data Source='(local)';Initial Catalog='pubs';Integrated Security=SSPI", "", "", 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();  
}  
  
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);  
}  

Consulte también

Objeto de conexión (ADO)
Propiedad DefaultDatabase
Propiedad de proveedor (ADO)