UpdateBatch and CancelBatch Methods Example (VC++)

This example demonstrates the UpdateBatch method in conjunction with the CancelBatch method.

// BeginUpdateBatchCpp
#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 "UpdateBatchX.h"

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

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

    UpdateBatchX();

    ::CoUninitialize();
}

//////////////////////////////////////////////////////////
//                                                      //
//      UpdateBatchX Function                           //
//                                                      //
//////////////////////////////////////////////////////////
void UpdateBatchX(void) 
{
   HRESULT  hr = S_OK;

    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _RecordsetPtr  pRstTitles   = NULL;

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

    IADORecordBinding *picRs    = NULL;    // Interface Pointer Declared
    CTitleRs titlers;             // C++ Class Object

    try
    {
        // Open titles table.
        TESTHR(pRstTitles.CreateInstance(__uuidof(Recordset)));
        pRstTitles->CursorType = adOpenKeyset;
        pRstTitles->LockType = adLockBatchOptimistic;
        pRstTitles->Open ("titles", strCnn,
            adOpenKeyset, adLockBatchOptimistic, adCmdTable);

        // Open IADORecordBinding interface pointer for binding 
        // Recordset to a class
        TESTHR(pRstTitles->QueryInterface(
            __uuidof(IADORecordBinding),(LPVOID*)&picRs));

        // Binding the Recordset to a C++ Class
        TESTHR(picRs->BindToRecordset(&titlers));
        pRstTitles->MoveFirst();

        // Loop through recordset and ask user if she wants,
        // to change the type for a specified title.
        while (!(pRstTitles->EndOfFile))
        {
            // Compare type with psychology
            if (!strcmp( (char *)strtok(titlers.m_szt_Type," "),
                "psychology" ))
            { 
                printf("\n\nTitle: %s \nChange type to self_help?(y/n):",
                    titlers.m_szt_Title);
                char chKey;
                chKey = getch();
                if(toupper(chKey) == 'Y')
                {
                    // Change type to self_help.
                    pRstTitles->Fields->GetItem("type")->Value = 
                        (_bstr_t)("self_help");
                }
            }
            pRstTitles->MoveNext();
        }

        // Ask the user if she wants to commit to all the 
        // changes made above.
        printf("\n\nSave all changes?");
        char chKey;
        chKey = getch();
        if(toupper(chKey) == 'Y')
        {
            pRstTitles->UpdateBatch(adAffectAll);
        }
        else
        {
            pRstTitles->CancelBatch(adAffectAll);
        }

        // Print current data in recordset.
        pRstTitles->Requery(adOptionUnspecified);

        // Open IADORecordBinding interface pointer for Binding Recordset to a class    
        TESTHR(pRstTitles->QueryInterface(
            __uuidof(IADORecordBinding),(LPVOID*)&picRs));

        // ReBinding the Recordset to a C++ Class.
        TESTHR(picRs->BindToRecordset(&titlers));

        // Move to the first record of the title table
        pRstTitles->MoveFirst();

        //Clear the screen for the next display.
        system("cls");

        while (!pRstTitles->EndOfFile)
        {
            printf("%s -  %s\n",
                titlers.lt_TitleStatus == adFldOK ? 
                titlers.m_szt_Title :"<NULL>",
                titlers.lt_TypeStatus == adFldOK ? 
                titlers.m_szt_Type :"<NULL>");
            pRstTitles->MoveNext();
        }

        pRstTitles->MoveFirst();

        // Restore original data because this is demonstration.
        while (!(pRstTitles->EndOfFile))
        {
            // Compare type with psychology
            if(!strcmp( (char *)strtok(titlers.m_szt_Type," "),
                "self_help" ))
            {
                // Change type to psychology.
                pRstTitles->Fields->GetItem("type")->Value = 
                    (_bstr_t)("psychology");
            }
            pRstTitles->MoveNext();
        }
    }
    catch (_com_error &e)
    {
       // Notify the user of errors if any.
       // Pass a connection pointer accessed from the Recordset.
        _variant_t vtConnect = pRstTitles->GetActiveConnection();

        // GetActiveConnection returns connect string if connection
        // is not open, else returns Connection object.
        switch(vtConnect.vt)
        {
            case VT_BSTR:
                PrintComError(e);
                break;
            case VT_DISPATCH:
                PrintProviderError(vtConnect);
                break;
            default:
                printf("Errors occured.");
                break;
        }
    }

    if (pRstTitles)
        if (pRstTitles->State == adStateOpen)
        {
            pRstTitles->UpdateBatch(adAffectAll);
            pRstTitles->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("Error number: %x\t%s\n", pErr->Number, 
                (LPCSTR) 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);
}
// EndUpdateBatchCpp

UpdateBatchX.h

// BeginUpdateBatchH
#include "icrsint.h"

//This class extracts titles and type from Titles table
class CTitleRs : public CADORecordBinding
{
BEGIN_ADO_BINDING(CTitleRs)
        // Column title is the 2nd field in the table
        ADO_VARIABLE_LENGTH_ENTRY2(2,adVarChar,m_szt_Title,
            sizeof(m_szt_Title),lt_TitleStatus,FALSE)
        // Column type is the 3rd field in the table
        ADO_VARIABLE_LENGTH_ENTRY2(3,adVarChar,m_szt_Type,
            sizeof(m_szt_Type),lt_TypeStatus,TRUE)
END_ADO_BINDING()

public:
    CHAR m_szt_Title[81];
    ULONG lt_TitleStatus;
    CHAR m_szt_Type[13];
    ULONG lt_TypeStatus;
};
// EndUpdateBatchH

See Also

CancelBatch Method | UpdateBatch Method