MDAC 2.5 SDK - ADO

Status Property Example (VC++)

See Also

This example uses the Status property to display which records have been modified in a batch operation before a batch update has occurred.

#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 "StatusX.h"

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

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

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

    StatusX();

    ::CoUninitialize();
}

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

    // Define string variables.
    _bstr_t strCnn("Provider=sqloledb;Data Source=srv;"
            "Initial Catalog=Pubs;User Id=sa;Password=;");

    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
     IADORecordBinding *picRs    = NULL;  // Interface Pointer Declared
     CTitleRs titlers;           // C++ Class Object
    _RecordsetPtr  pRstTitles    = NULL;
    LPSTR p_TempStr        = NULL;

       try
    {
        // Open recordset for batch update
        TESTHR(pRstTitles.CreateInstance(__uuidof(Recordset)));
        pRstTitles->CursorType = adOpenKeyset;
        pRstTitles->LockType = adLockBatchOptimistic;
        pRstTitles->Open ("Titles", strCnn,
            adOpenKeyset, adLockBatchOptimistic, adCmdTable);

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

        // Bind the Recordset to a C++ class here 
        TESTHR(picRs->BindToRecordset(&titlers));

        p_TempStr = (LPSTR) malloc(sizeof(titlers.m_szt_Type));

        // Change the type of psychology titles.
        while(!(pRstTitles->EndOfFile))
        {
            // Remove blank string(trim) 
            strcpy(p_TempStr,strtok(titlers.m_szt_Type," "));

            // Compare the type of psychology titles
            if (!strcmp(p_TempStr,"psychology")) 
            { 
                    // Copy "self_help" title field
                    pRstTitles->Fields->GetItem("type")->Value = 
                        (_bstr_t) ("self_help");
            }
            pRstTitles->MoveNext();
        }

        // Display Title ID and status
        pRstTitles->MoveFirst();
        while(!(pRstTitles->EndOfFile))
        {
            if(pRstTitles->Status == adRecModified)
            {
                printf("%s - Modified\n",titlers.lt_Title_idStatus == 
                    adFldOK ? titlers.m_szt_Title_id : "<NULL>");
            }
            else
            {
                printf("%s\n",titlers.lt_Title_idStatus == adFldOK ? 
                    titlers.m_szt_Title_id : "<NULL>");
            }
            pRstTitles->MoveNext();
        }

        // Deallocate the memory
        free(p_TempStr);

        // Cancel the update because this is a demonstration.
        pRstTitles->CancelBatch(adAffectAll);
        pRstTitles->Close();
    }
    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;
        }
    }
}

///////////////////////////////////////////////
//                                           //
//    PrintProviderError Function            //
//                                           //
///////////////////////////////////////////////

void PrintProviderError(_ConnectionPtr pConnection)
{
    // Print Provider Errors from Connection object.
    // pErr is a record object in the Connection’s Errors 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);
}

StatusX.h

#include "icrsint.h"

//This class extracts title_id and type from Titles table.
class CTitleRs : public CADORecordBinding
{
    BEGIN_ADO_BINDING(CTitleRs)
        // Column title_id is the 1st field in the table
        ADO_VARIABLE_LENGTH_ENTRY2(1,adVarChar,m_szt_Title_id,
            sizeof(m_szt_Title_id),lt_Title_idStatus,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_id[7];
    ULONG lt_Title_idStatus;
    CHAR m_szt_Type[13];
    ULONG lt_TypeStatus;
};