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Provider and DefaultDatabase Properties Example (VC++)

This example demonstrates the Provider property by opening three Connection objects using different providers. It also uses the DefaultDatabase property to set the default database for the Microsoft ODBC Provider.

// 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);
}
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