mfc 连接sqlserver2000 数据问题

在OpenDaabase这个函数里，提示我     ：错误    1    error C2065: 'adModeUnkown' : undeclared identifier    c:\bs\kaoqin\kaoqin\wh.cpp    119      大侠路过看看啊，，谢谢了



_bstr_t strConnect;
    strConnect="Provider=SQLOLEDB.1;Persist Security Info=False;User ID=sa;Initial Catalog=Student;Data Source=(local)";
    HRESULT hr;
    try
    {
        hr=m_pConnection.CreateInstance(_uuidof(Connection));
        if(SUCCEEDED(hr))
        {  
            hr= m_pConnection->Open(strConnect,"","",adModeUnkown );
        }
    }