MFC中,在界面上有一个DataGrid,想在程序初始化时让它从SQL Server中读取数据显示,但不知道如何给它指定数据源.因为程序运行过程中,可能会改变它的数据源,所以不想使用ADODC做数据源.请问如何解决?请大侠指教.CDataGrid有一个方法,好像是指定数据源的,但不知参数如何传递.
void CDataGrid::SetRefDataSource(LPUNKNOWN newValue)
{
static BYTE parms[] =
VTS_UNKNOWN;
InvokeHelper(0x2a, DISPATCH_PROPERTYPUTREF, VT_EMPTY, NULL, parms,
newValue);
}
查到 LPUNKNOWN 的类型是 typedef IUnknown* LPUNKNOWN;IUnknown的定义为:
IUnknown
{
public:
BEGIN_INTERFACE
virtual HRESULT STDMETHODCALLTYPE QueryInterface(
/* [in] */ REFIID riid,
/* [iid_is][out] */ void __RPC_FAR *__RPC_FAR *ppvObject) = 0;
virtual ULONG STDMETHODCALLTYPE AddRef( void) = 0;
virtual ULONG STDMETHODCALLTYPE Release( void) = 0;#if (_MSC_VER >= 1200) // VC6 or greater
template <class Q>
HRESULT STDMETHODCALLTYPE QueryInterface(Q** pp)
{
return QueryInterface(__uuidof(Q), (void**)pp);
}
#endif END_INTERFACE
};好像是一个接口,不知如何使用,郁闷!
void CDataGrid::SetRefDataSource(LPUNKNOWN newValue)
{
static BYTE parms[] =
VTS_UNKNOWN;
InvokeHelper(0x2a, DISPATCH_PROPERTYPUTREF, VT_EMPTY, NULL, parms,
newValue);
}
查到 LPUNKNOWN 的类型是 typedef IUnknown* LPUNKNOWN;IUnknown的定义为:
IUnknown
{
public:
BEGIN_INTERFACE
virtual HRESULT STDMETHODCALLTYPE QueryInterface(
/* [in] */ REFIID riid,
/* [iid_is][out] */ void __RPC_FAR *__RPC_FAR *ppvObject) = 0;
virtual ULONG STDMETHODCALLTYPE AddRef( void) = 0;
virtual ULONG STDMETHODCALLTYPE Release( void) = 0;#if (_MSC_VER >= 1200) // VC6 or greater
template <class Q>
HRESULT STDMETHODCALLTYPE QueryInterface(Q** pp)
{
return QueryInterface(__uuidof(Q), (void**)pp);
}
#endif END_INTERFACE
};好像是一个接口,不知如何使用,郁闷!
{
_CommandPtr cmd;
_RecordsetPtr rs;
_ConnectionPtr conn;
_variant_t vra;
VARIANT *vt1 = NULL;
try
{
/* cmd.CreateInstance( __uuidof(Command));
rs.CreateInstance(__uuidof(Recordset));
conn.CreateInstance(__uuidof(Connection));*/ UpdateData(TRUE);
theApp.m_pConnection->PutCursorLocation(adUseClient);
/* conn->CursorLocation = adUseClient;
conn->Open(_bstr_t( theApp.m_pConnection.GetInterfacePtr() ), L"", L"", -1);
cmd->ActiveConnection = conn;
cmd->CommandText = (_bstr_t) m_strQuery;
cmd->CommandType = adCmdText;
rs = cmd->Execute(&vra,vt1, adCmdText);*/
/*rs->PutRefActiveConnection(theApp.m_pConnection);
rs->Open((_bstr_t)m_strQuery,
theApp.m_pConnection.GetInterfacePtr(),
adOpenDynamic,
adLockOptimistic,
adCmdText);*/
/// ((CTestDllApp*)(&theApp))->m_pConnection
/// m_pRecordset.CreateInstance(__uuidof(Recordset));
/* m_pRecordset->Open((_bstr_t)m_strQuery,
_variant_t((IDispatch*)theApp.m_pConnection, TRUE),
adOpenStatic,
adLockOptimistic,
adCmdText);*/
if(m_pRecordset->State==1)
{
m_pRecordset->Close();
}
m_pRecordset->Open((_bstr_t)m_strQuery,
theApp.m_pConnection.GetInterfacePtr(),//»ñÈ¡¿â½Ó¿âµÄIDispatchÖ¸Õë
adOpenStatic,
adLockOptimistic,
adCmdText);
/* m_DataGrid.SetRefDataSource(NULL);
m_DataGrid.SetRefDataSource((LPUNKNOWN)m_pRecordset);
m_DataGrid.Refresh();*/
}
catch (_com_error &e)
{
::MessageBox(NULL,e.Description(),"Ìáʾ",MB_OK);
}
m_DataGrid.SetRefDataSource((LPUNKNOWN)m_pRecordset);
m_DataGrid.Refresh();
UpdateData(FALSE);
//m_pRecordset->Close();
return true;
}