在DAO多线程处理中，有许多局限性，所以我设计了这么一个类，通过GUI线程来使用DAO的强制调用。在类中使用了GUI的消息队列，所有进入到CMultiDAORecordset的调用都被迫使用AfxGetThread()来检查当前的线程。GUI线程指针是放在InitInstance的首端，如果在GUI线程中，引入的调用请求不在运行，那么CMultiDAORecordSet就会发送一个WM_MULTIDAOMESSAGE消息给AfxGetMainWnd()（在Mainfrm.cpp中）。Mainfrm接受到这个消息，线程也就要再运行一次，这个时候，消息已经接受了，基类CDaoRecordset也就得到了调用。所以你的类是从CMultiDAORecordset继承的，而不是CDaoRecordset，如下：

class CMySet : public CMultiDaoRecordSet

在相应的CPP文件中也应该改一下：

IMPLEMENT_DYNAMIC(CMySet, CMultiDaoRecordSet)

CMySet::CMySet (CDaoDatabase* pdb) : CMultiDaoRecordSet(pdb)
为了处理接受到的WM_MULTIDAOMESSAGE消息，下面的代码还应该加在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();
brea