UpdateBatch and CancelBatch Methods Example (VC++)
This example demonstrates the UpdateBatch method in conjunction with the CancelBatch method.
// BeginUpdateBatchCpp
#import "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