Export (0) Print
Expand All
Expand Minimize

ConnectionString, ConnectionTimeout, and State Properties Example (VC++)

This example demonstrates different ways of using the ConnectionString property to open a Connection object. It also uses the ConnectionTimeout property to set a connection timeout period, and the State property to check the state of the connections. The GetState function is required for this procedure to run.

Note Note

If you are connecting to a data source provider that supports Windows authentication, you should specify Trusted_Connection=yes or Integrated Security = SSPI instead of user ID and password information in the connection string.

// ConnectionStringSampleCpp.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 ConnectionStringX();
_bstr_t GetState(int intState); 
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

int main() {
   if (FAILED(::CoInitialize(NULL)))
      return 0;

   ConnectionStringX();
   ::CoUninitialize();
}

void ConnectionStringX() {
   // Define Connection object pointers.  Initialize pointers on define.  These are in the ADODB::  namespace
   _ConnectionPtr pConnection1 = NULL;
   _ConnectionPtr pConnection2 = NULL;
   _ConnectionPtr pConnection3 = NULL;
   _ConnectionPtr pConnection4 = NULL;

   // Define Other Variables
   HRESULT hr = S_OK;

   try {
      // Open a connection using OLE DB syntax.
      TESTHR(pConnection1.CreateInstance(__uuidof(Connection)));
      pConnection1->ConnectionString = "Provider='sqloledb';Data Source='(local)';"
         "Initial Catalog='Pubs';Integrated Security='SSPI';";
      pConnection1->ConnectionTimeout = 30;
      pConnection1->Open("", "", "",adConnectUnspecified);
      printf("cnn1 state: %s\n", (LPCTSTR)GetState(pConnection1->State));

      // Open a connection using a DSN and ODBC tags.
      // It is assumed that you have create DSN 'DataPubs' with a user name as 
      // 'MyUserId' and password as 'MyPassword'.
      TESTHR(pConnection2.CreateInstance(__uuidof(Connection)));
      pConnection2->ConnectionString = "DSN=DataPubs;UID=MyUserId;PWD=MyPassword;";
      pConnection2->Open("", "", "", adConnectUnspecified);
      printf("cnn2 state: %s\n", (LPCTSTR)GetState(pConnection2->State));

      // Open a connection using a DSN and OLE DB tags.
      TESTHR(pConnection3.CreateInstance(__uuidof(Connection)));
      pConnection3->ConnectionString = "Data Source=DataPubs;";
      pConnection3->Open("", "", "", adConnectUnspecified);
      printf("cnn3 state: %s\n", (LPCTSTR)GetState(pConnection3->State));

      // Open a connection using a DSN and individual arguments instead of a connection string.
      // It is assumed that you have create DSN 'DataPubs' with a user name as 
      // 'MyUserId' and password as 'MyPassword'.
      TESTHR(pConnection4.CreateInstance(__uuidof(Connection)));
      pConnection4->Open("DataPubs", "MyUserId", "MyPassword", adConnectUnspecified);
      printf("cnn4 state: %s\n", (LPCTSTR)GetState(pConnection4->State));
   }
   catch(_com_error &e) {
      // Notify user of any errors.  Pass a connection pointer accessed from the Connection.
      PrintProviderError(pConnection1);
      if (pConnection2)
         PrintProviderError(pConnection2);

      if (pConnection3)
         PrintProviderError(pConnection3);

      if (pConnection4)
         PrintProviderError(pConnection4);

      PrintComError(e);
   }

   // Cleanup objects before exit.
   if (pConnection1)
      if (pConnection1->State == adStateOpen)
         pConnection1->Close();

   if (pConnection2)
      if (pConnection2->State == adStateOpen)
         pConnection2->Close();

   if (pConnection3)
      if (pConnection3->State == adStateOpen)
         pConnection3->Close();

   if (pConnection4)
      if (pConnection4->State == adStateOpen)
         pConnection4->Close();
}

_bstr_t GetState(int intState) {
   _bstr_t strState; 
   switch(intState) {
   case adStateClosed:
      strState = "adStateClosed";
      break;
   case adStateOpen:
      strState = "adStateOpen";
      break;
   default:
      ;
   }
   return strState;
}

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);
}
Show:
© 2014 Microsoft