Prepared Property Example (VC++)

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

// BeginPreparedCpp
#import "c:\Program Files\Common Files\System\ADO\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);
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

///////////////////////////////////////////////////////////
//                                                       //
//      Main Function                                    //
//                                                       //
///////////////////////////////////////////////////////////

void main()
{
    if(FAILED(::CoInitialize(NULL)))
        return;

    PreparedX();

    ::CoUninitialize();
}

///////////////////////////////////////////////////////////
//                                                       //
//      PreparedX Function                               //
//                                                       //
///////////////////////////////////////////////////////////

void PreparedX(void) 
{
    // 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='MySqlServer';"
            "Initial Catalog='pubs';Integrated Security='SSPI';");

    //Define Other Variables
    HRESULT   hr = S_OK;

    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 prepared.
        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(intLoop=1;intLoop<=20;intLoop++)
        {
            pCmd2->Execute(NULL,NULL,adCmdText);
        }
        sngEnd=GetTickCount(); 

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

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

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

See Also

Command Object | Prepared Property