Visual C++多線程DAO處理

　　在DAO多線程處理中，有許多局限性，所以我設計了這么一個類，通過GUI線程來使用DAO的強制調用。在類中使用了GUI的消息隊列，所有進入到CMultiDAORecordset的調用都被迫使用AfxGetThread()來檢查當前的線程。GUI線程指針是放在InitInstance的首端，如果在GUI線程中，引入的調用請求不在運行，那么CMultiDAORecordSet就會發送一個WM_MULTIDAOMESSAGE消息給AfxGetMainWnd()（在Mainfrm.cpp中）。Mainfrm接受到這個消息，線程也就要再運行一次，這個時候，消息已經接受了，基類CDaoRecordset也就得到了調用。所以你的類是從CMultiDAORecordset繼承的，而不是CDaoRecordset，如下：

class CMySet : public CMultiDaoRecordSet

在相應的CPP文件中也應該改一下：

IMPLEMENT_DYNAMIC(CMySet, CMultiDaoRecordSet)

CMySet::CMySet (CDaoDatabase* pdb) : CMultiDaoRecordSet(pdb)
為了處理接受到的WM_MULTIDAOMESSAGE消息，下面的代碼還應該加在MainFrm中：

在MainFrm.h文件中加：
#ifdef MAINFRAME_CPP
UINT WM_MULTIDAOMESSAGE = RegisterWindowMessage("WM_MULTIDAOMESSAGE");
#else
extern UINT WM_MULTIDAOMESSAGE;
#endif

afx_msg LONG OnMultiDaoMessage( UINT uParam, LONG lParam);
在MainFrm.cpp文件中加：
#define MAINFRAME_CPP

#include "MutliDaoRecordset.h"

//added to the message map

BEGIN_MESSAGE_MAP(CMainFrame, CMDIFrameWnd)
//{{AFX_MSG_MAP(CMainFrame)
ON_REGISTERED_MESSAGE(WM_MULTIDAOMESSAGE, OnMultiDaoMessage)
END_MESSAGE_MAP()

//this function added
LONG CMainFrame::OnMultiDaoMessage( UINT uParam, LONG lParam)
{
//jtm
//based on switch, perform operation...
CMultiDaoRecordSet *pSet = (CMultiDaoRecordSet *)lParam;
LONG lRet = 0;

CString cRet = "";
COleVariant cVar;

try
{
//jtm-------debug--------------------------------------
CString cTraceMessage = cDAOMessageArray[uParam];
cTraceMessage += "\n";
TRACE(cTraceMessage);
//jtm-------debug--------------------------------------

switch(uParam)
{
case MultiDaoOpen:
pSet->Open();
break;
case MultiDaoClose:
pSet->Close();
break;
case MultiDaoIsOpen:
lRet = (LONG)pSet->IsOpen();
break;
case MultiDaoIsBOF:
lRet = (LONG)pSet->IsBOF();
break;
case MultiDaoIsEOF:
lRet = (LONG)pSet->IsEOF();
break;
case MultiDaoIsDeleted:
lRet = (LONG)pSet->IsDeleted();
break;
case MultiDaoIsFieldDirty:
lRet = (LONG)pSet->IsFieldDirty(pSet->pParam1);
break;
case MultiDaoIsFieldNull:
lRet = (LONG)pSet->IsFieldNull(pSet->pParam1);
break;
case MultiDaoIsFieldNullable:
lRet = (LONG)pSet->IsFieldNullable(pSet->pParam1);
break;
case MultiDaoGetName:
cRet = pSet->GetName();
lRet = (LONG)&cRet;
break;
case MultiDaoGetType:
lRet = (LONG)pSet->GetType();
break;
case MultiDaoGetEditMode:
lRet = (LONG)pSet->GetEditMode();
break;
case MultiDaoGetLastModifiedBookmark:
cVar = pSet->GetLastModifiedBookmark();
lRet = (LONG)&cVar;
break;
case MultiDaoGetRecordCount:
lRet = (LONG)pSet->GetRecordCount();
break;
case MultiDaoMoveNext:
pSet->MoveNext();
break;
case MultiDaoMovePrev:
pSet->MovePrev();
break;
case MultiDaoMoveFirst:
pSet->MoveFirst();
break;
case MultiDaoMoveLast:
pSet->MoveLast();
break;
case MultiDaoMove:
pSet->Move(*(LONG *)pSet->pParam1);
break;
case MultiDaoFindNext:
lRet = (LONG)pSet->FindNext(*(LPCTSTR *)pSet->pParam1);
break;
case MultiDaoFindPrev:
lRet = (LONG)pSet->FindPrev(*(LPCTSTR*)pSet->pParam1);
break;
case MultiDaoFindFirst:
lRet = (LONG)pSet->FindFirst(*(LPCTSTR *)pSet->pParam1);
break;
case MultiDaoFindLast:
lRet = (LONG)pSet->FindLast(*(LPCTSTR *)pSet->pParam1);
break;
case MultiDaoFind:
lRet = (LONG)pSet->Find(*(LONG *)pSet->pParam1, *(LPCTSTR*)pSet->pParam2);
break;
case MultiDaoGetBookmark:
cVar = pSet->GetBookmark();
lRet = (LONG)&cVar;
break;
case MultiDaoSetBookmark:
pSet->SetBookmark(*(COleVariant*)pSet->pParam1);
break;
case MultiDaoAddNew:
pSet->AddNew();
break;
case MultiDaoEdit:
pSet->Edit();
break;
case MultiDaoUpdate:
pSet->Update();
break;
case MultiDaoDelete:
pSet->Delete();
break;
case MultiDaoCancelUpdate:
pSet->CancelUpdate();
break;
case MultiDaoRequery:
pSet->Requery();
break;
}
}
catch (CDaoException *e)
{
TRACE("Database Multithread Operation Failed%s\n",
e->m_pErrorInfo->m_strDescription);
}
return lRet;
}

下面的代碼是加在對應的應用程序對象的頭文件中的：
public:
CWinThread *pGUIThread;

And this to the constructor in the app .cpp file:


CMyApp::CMyApp()
{
pGUIThread = AfxGetThread();
}


　　如果沒有上面的定義的話，你的應用程序就會出問題。整個DAO公共函數并沒有全部實現，但不管怎么樣，上面的函數是保護CDaoRecordset的使用的。如果你要加個函數的話，加進去就行了，你也可以用一個對話框來顯示錯誤信息，它們都應該在MultiDaorecordset.h中被定義。為了支持DAO多線程的類，下面的代碼也應該加進去：

加在Multidaorecordset.cpp中：
// MultiDaoRecordSet.cpp : implementation file
//

#define MULTIDAORECORDSET_CPP

#include "stdafx.h"

#include "MyApp.h"

#include "MultiDaoRecordSet.h"

#include "mainfrm.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CMultiDaoRecordSet

IMPLEMENT_DYNAMIC(CMultiDaoRecordSet, CDaoRecordset)

CMultiDaoRecordSet::CMultiDaoRecordSet(CDaoDatabase* pdb)
: CDaoRecordset(pdb)
{
//{{AFX_FIELD_INIT(CMultiDaoRecordSet)
//}}AFX_FIELD_INIT
m_nDefaultType = dbOpenDynaset;
}

//jtm
//thread safe destructor....
CMultiDaoRecordSet::~CMultiDaoRecordSet()
{
if (IsOpen())
Close();

// Clean up database if necessary
if (m_pDatabase != NULL && (m_nStatus & AFX_DAO_IMPLICIT_DB))
{
m_pDatabase->Close();
delete m_pDatabase;
m_pDatabase = NULL;
}
}

CString CMultiDaoRecordSet::GetDefaultDBName()
{
CMyApp *pApp = ((CMYApp *)AfxGetApp());
return pApp->GetDatabaseFullPath();
}

/////////////////////////////////////////////////////////////////////////////
// CMultiDaoRecordSet diagnostics

//jtm
//multi thread safe functoins
void CMultiDaoRecordSet::Open(int nOpenType, LPCTSTR lpszSQL, int nOptions)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::Open(nOpenType, lpszSQL, nOptions);
}
else
{
pParam1 = (void *)&nOpenType;
pParam2 = (void *)lpszSQL;
pParam3 = (void *)&nOptions;
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoOpen, (LPARAM)this);
}
}

void CMultiDaoRecordSet::Close()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::Close();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoClose, (LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::IsOpen()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::IsOpen();
}
else
{
return (BOOL)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoIsOpen, (LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::IsBOF()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::IsBOF();
}
else
{
return (BOOL)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoIsBOF, (LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::IsEOF()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::IsEOF();
}
else
{
return (BOOL)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoIsEOF, (LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::IsDeleted()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::IsDeleted();
}
else
{
return (BOOL)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoIsDeleted, (LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::IsFieldDirty(void* pv)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::IsFieldDirty(pv);
}
else
{
pParam1 = pv;
return (BOOL)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoIsFieldDirty, (LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::IsFieldNull(void* pv)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::IsFieldNull(pv);
}
else
{
pParam1 = pv;
return (BOOL)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoIsFieldNull, (LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::IsFieldNullable(void* pv)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::IsFieldNullable(pv);
}
else
{
pParam1 = pv;
return (BOOL)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoIsFieldNullable, (LPARAM)this);
}
}

CString CMultiDaoRecordSet::GetName()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::GetName();
}
else
{
return (CString)*(CString *)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoGetName, (LPARAM)this);
}
}

short CMultiDaoRecordSet::GetType()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::GetType();
}
else
{
return (short)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoGetType, (LPARAM)this);
}
}

short CMultiDaoRecordSet::GetEditMode()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::GetEditMode();
}
else
{
return (short)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoGetEditMode, (LPARAM)this);
}
}

CString CMultiDaoRecordSet::GetSQL()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::GetSQL();
}
else
{
return (CString)*(CString *)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoGetSQL, (LPARAM)this);
}
}

COleVariant CMultiDaoRecordSet::GetLastModifiedBookmark()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::GetLastModifiedBookmark();
}
else
{
return (COleVariant)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoGetLastModifiedBookmark, (LPARAM)this);
}
}

long CMultiDaoRecordSet::GetRecordCount()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::GetRecordCount();
}
else
{
return (long)AfxGetMainWnd()->
SendMessage(WM_MULTIDAOMESSAGE, MultiDaoGetRecordCount, (LPARAM)this);
}
}

void CMultiDaoRecordSet::MoveNext()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::MoveNext();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoMoveNext,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::MovePrev()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::MovePrev();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoMovePrev,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::MoveFirst()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::MoveFirst();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoMoveFirst,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::MoveLast()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::MoveLast();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoMoveLast,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::Move(long lRows)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::Move(lRows);
}
else
{
pParam1 = (void *)&lRows;
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoMove,
(LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::FindNext(LPCTSTR lpszFilter)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::FindNext(lpszFilter);
}
else
{
pParam1 = (void *)lpszFilter;
return (BOOL)AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoFindNext,
(LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::FindPrev(LPCTSTR lpszFilter)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::FindPrev(lpszFilter);
}
else
{
pParam1 = (void *)lpszFilter;
return (BOOL)AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoFindPrev,
(LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::FindFirst(LPCTSTR lpszFilter)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::FindFirst(lpszFilter);
}
else
{
pParam1 = (void *)lpszFilter;
return (BOOL)AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoFindFirst,
(LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::FindLast(LPCTSTR lpszFilter)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::FindLast(lpszFilter);
}
else
{
pParam1 = (void *)lpszFilter;
return (BOOL)AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoFindLast,
(LPARAM)this);
}
}

BOOL CMultiDaoRecordSet::Find(long lFindType, LPCTSTR lpszFilter)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::Find(lFindType, lpszFilter);
}
else
{
pParam1 = (void *)&lFindType;
pParam2 = (void *)lpszFilter;
return (BOOL)AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoFind,
(LPARAM)this);
}
}

COleVariant CMultiDaoRecordSet::GetBookmark()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
return CDaoRecordset::GetBookmark();
}
else
{
return AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoGetBookmark,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::SetBookmark(COleVariant varBookmark)
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::SetBookmark(varBookmark);
}
else
{
pParam1 = (void *)&varBookmark;
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoSetBookmark,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::AddNew()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::AddNew();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoAddNew,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::Edit()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::Edit();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoEdit,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::Update()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::Update();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoUpdate,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::Delete()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::Delete();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoDelete,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::CancelUpdate()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::CancelUpdate();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoCancelUpdate,
(LPARAM)this);
}
}

void CMultiDaoRecordSet::Requery()
{
CMYApp *pApp = ((CMYApp *)AfxGetApp());
if (pApp->pGUIThread == AfxGetThread())
{
CDaoRecordset::Requery();
}
else
{
AfxGetMainWnd()->SendMessage(WM_MULTIDAOMESSAGE, MultiDaoRequery,
(LPARAM)this);
}
}

and, Multidaorecordset.h


#if !defined(AFX_MULTIDAORECORDSET_H__BECC8DC3_A967_11D2_BA4C_006097808646__INCLUDED_)
#define AFX_MULTIDAORECORDSET_H__BECC8DC3_A967_11D2_BA4C_006097808646__INCLUDED_

#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000
// MultiDaoRecordSet.h : header file
//

/////////////////////////////////////////////////////////////////////////////
// CMultiDaoRecordSet DAO recordset

enum {
MultiDaoOpen,
MultiDaoClose,
MultiDaoIsOpen,
MultiDaoIsBOF,
MultiDaoIsEOF,
MultiDaoIsDeleted,
MultiDaoIsFieldDirty,
MultiDaoIsFieldNull,
MultiDaoIsFieldNullable,
MultiDaoGetName,
MultiDaoGetType,
MultiDaoGetSQL,
MultiDaoGetEditMode,
MultiDaoGetLastModifiedBookmark,
MultiDaoGetRecordCount,
MultiDaoMoveNext,
MultiDaoMovePrev,
MultiDaoMoveFirst,
MultiDaoMoveLast,
MultiDaoMove,
MultiDaoFindNext,
MultiDaoFindPrev,
MultiDaoFindFirst,
MultiDaoFindLast,
MultiDaoFind,
MultiDaoGetBookmark,
MultiDaoSetBookmark,
MultiDaoAddNew,
MultiDaoEdit,
MultiDaoUpdate,
MultiDaoDelete,
MultiDaoCancelUpdate,
MultiDaoRequery,
};

#ifdef MULTIDAORECORDSET_CPP
CString cDAOMessageArray[] =
{
"MultiDaoOpen",
"MultiDaoClose",
"MultiDaoIsOpen",
"MultiDaoIsBOF",
"MultiDaoIsEOF",
"MultiDaoIsDeleted",
"MultiDaoIsFieldDirty",
"MultiDaoIsFieldNull",
"MultiDaoIsFieldNullable",
"MultiDaoGetName",
"MultiDaoGetType",
"MultiDaoGetSQL",
"MultiDaoGetEditMode",
"MultiDaoGetLastModifiedBookmark",
"MultiDaoGetRecordCount",
"MultiDaoMoveNext",
"MultiDaoMovePrev",
"MultiDaoMoveFirst",
"MultiDaoMoveLast",
"MultiDaoMove",
"MultiDaoFindNext",
"MultiDaoFindPrev",
"MultiDaoFindFirst",
"MultiDaoFindLast",
"MultiDaoFind",
"MultiDaoGetBookmark",
"MultiDaoSetBookmark",
"MultiDaoAddNew",
"MultiDaoEdit",
"MultiDaoUpdate",
"MultiDaoDelete",
"MultiDaoCancelUpdate",
"MultiDaoRequery",
};
#else
extern CString cDAOMessageArray[];
#endif

class CMultiDaoRecordSet : public CDaoRecordset
{
public:

//jtm
//FORCE user to pass database...
CMultiDaoRecordSet(CDaoDatabase* pDatabase);

~CMultiDaoRecordSet();

DECLARE_DYNAMIC(CMultiDaoRecordSet)

// Field/Param Data
//{{AFX_FIELD(CMultiDaoRecordSet, CDaoRecordset)
//}}AFX_FIELD

// Overrides
// ClassWizard generated virtual function overrides
//{{AFX_VIRTUAL(CMultiDaoRecordSet)
public:
virtual CString GetDefaultDBName(); // Default database name
//}}AFX_VIRTUAL

// Implementation
//jtm
//redefined public functions
//Note: I am only redefining SOME
//of the public functions this is NOT
//a FULL implementation !!!!!!
public:
//jtm -- only supporting this open.....
virtual void Open(int nOpenType = AFX_DAO_USE_DEFAULT_TYPE,
LPCTSTR lpszSQL = NULL, int nOptions = 0);
virtual void Close();
BOOL IsOpen();
BOOL IsBOF();
BOOL IsEOF();
BOOL IsDeleted();
BOOL IsFieldDirty(void* pv);
BOOL IsFieldNull(void* pv);
BOOL IsFieldNullable(void* pv);
CString GetName();
short GetType();
short GetEditMode();
CString GetSQL();
COleVariant GetLastModifiedBookmark();
long GetRecordCount();
void MoveNext();
void MovePrev();
void MoveFirst();
void MoveLast();
virtual void Move(long lRows);
BOOL FindNext(LPCTSTR lpszFilter);
BOOL FindPrev(LPCTSTR lpszFilter);
BOOL FindFirst(LPCTSTR lpszFilter);
BOOL FindLast(LPCTSTR lpszFilter);
virtual BOOL Find(long lFindType, LPCTSTR lpszFilter);
COleVariant GetBookmark();
void SetBookmark(COleVariant varBookmark);
virtual void AddNew();
virtual void Edit();
virtual void Update();
virtual void Delete();
virtual void CancelUpdate();
virtual void Requery();

void *pParam1;
void *pParam2;
void *pParam3;
};

//{{AFX_INSERT_LOCATION}}
// Microsoft Developer Studio will insert additional declarations immediately before the //previous line.

#endif // !defined(AFX_MULTIDAORECORDSET_H__BECC8DC3_A967_11D2_BA4C_006097808646__INCLUDED_)



　　調試的東西等你搞好你的程序后就可以刪了，不過要注意，不要直接調用CDaoRecordset，否則，你的應用程序就會問題。我試了一下，使用這個類的時候，你的計算機的速度會稍微的暫停幾秒鐘(正在運行你的程序)，不過這不會影響到你的計算機的使用的，因為這個類DAO的調用是通過GUI的，如果你使用不當的話(比如臨界區問題)就會導致計算機的死鎖。

原文轉自：http://www.kjueaiud.com