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Prepared Property Example (VC++)

This example demonstrates the Prepared property by opening two Command objects — one prepared and one not prepared.

// Prepared_Property_Sample.cpp
// compile with: /EHsc
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")

#include <ole2.h>
#include <stdio.h>
#include <conio.h>
#include <winbase.h>

// Function declarations
inline void TESTHR(HRESULT x) { if FAILED(x) _com_issue_error(x); };
void PreparedX();
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

int main() {
   if ( FAILED(::CoInitialize(NULL)) )
      return -1;

   PreparedX();
   ::CoUninitialize();
}

void PreparedX() {
   // Define ADO object pointers.  Initialize pointers on define.
   // These are in the ADODB:: namespace.
   _ConnectionPtr pConnection = NULL;
   _CommandPtr pCmd1 = NULL;
   _CommandPtr pCmd2 = NULL;

   // Define string variables.  
   _bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");

   try {
      // Open a connection.
      TESTHR(pConnection.CreateInstance(__uuidof(Connection)));
      pConnection->Open (strCnn, "", "", adConnectUnspecified);

      _bstr_t strCmd ("SELECT title,type FROM titles ORDER BY type");

      // Create two command objects for the same command; one prepared and one not.
      TESTHR(pCmd1.CreateInstance(__uuidof(Command)));
      pCmd1->ActiveConnection = pConnection;
      pCmd1->CommandText = strCmd;

      TESTHR(pCmd2.CreateInstance(__uuidof(Command)));
      pCmd2->ActiveConnection = pConnection;
      pCmd2->CommandText = strCmd;
      pCmd2->PutPrepared(true);

      // Set a timer,then execute the unprepared command 20 times.
      DWORD sngStart = GetTickCount(); 

      for ( int intLoop = 1 ; intLoop <= 20 ; intLoop++ )
         pCmd1->Execute(NULL, NULL, adCmdText);

      DWORD sngEnd=GetTickCount(); 
      float sngNotPrepared = (float)(sngEnd - sngStart) / (float)1000;

      // Reset the timer,then execute the prepared command 20 times
      sngStart = GetTickCount(); 
      for ( int intLoop = 1 ; intLoop <= 20 ; intLoop++ )
         pCmd2->Execute(NULL, NULL, adCmdText);

      sngEnd=GetTickCount(); 

      float sngPrepared = (float)(sngEnd - sngStart) / (float)1000;

      // Display performance results
      printf("Performance Results:");
      printf("\n\nNot Prepared: %6.3f seconds", sngNotPrepared);
      printf("\nPrepared:     %6.3f seconds", sngPrepared);
   }
   catch (_com_error &e) {
      // Display errors, if any. Pass a connection pointer accessed from the Connection.
      PrintProviderError(pConnection);
      PrintComError(e);
   }

   if (pConnection)
      if (pConnection->State == adStateOpen)
         pConnection->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("\t Error number: %x\t%s", pErr->Number, 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);
}
Performance Results:

Not Prepared:  0.016 seconds
Prepared:      0.016 seconds
Show:
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