初学ADO技术，老是runtime error

初学ADO技术，总是runtime error
CoInitialize(NULL);
    _ConnectionPtr pConn(__uuidof( Connection ));
    _RecordsetPtr pst(__uuidof(Recordset));
pConn->ConnectionString="Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=lyx;Data Source=XP-201203202245";
    pConn->Open("","","",adModeUnknown);
    //pst=pConn->Execute("insert into Student values('2016','陆','男',24,'sf')",NULL,adCmdText);
    //pConn->Execute("insert into Student values('2014','陆','男',24,'sf')",NULL,adCmdText);
pst->Open("select * from Student",pConn.GetInterfacePtr(),adOpenStatic,adLockOptimistic,adCmdText);
pst->Open("insert into Student values('2020','陆','男',24,'sf')",pConn.GetInterfacePtr(),adOpenStatic,adLockOptimistic,adCmdText);
    pst->AddNew();
 pst->PutCollect("Sname",_variant_t("8"));
 pst->Update();
    while(!pst->rsEOF)
{
((CListBox *)GetDlgItem(IDC_LIST1))->AddString((_bstr_t)pst->GetCollect("Sno"));
pst->MoveNext();
}
pst->Close();
    pConn->Close();
    pConn.Release();
    pst.Release();
CoUninitialize();
要是添加部分 pst->AddNew();
 pst->PutCollect("Sname",_variant_t("8"));
 pst->Update();
    while(!pst->rsEOF)注释掉，运行无错误，加上就弹出runtime error。看了网上很多教程，别人这么做都可以，为什么到了我这就不行了呢，请高手不吝赐教（其中Sname为char(9)）……
------解决方案--------------------
异常捕获改成这样看是什么错误

try

{

//你的ADO代码

}

catch (_com_error& e)

{

CString strMsg;

strMsg.Format(_T("错误描述：%s\n错误消息%s"), 

		(LPCTSTR)e.Description(),

		(LPCTSTR)e.ErrorMessage());

AfxMessageBox(strMsg);

}