插入数据insert语句中出错：没有与这些操作数匹配的“+”运算符，操作数类型为：const char[ ]+CString

UpdateData();
        CString n;
        n.Format(L"%d", m_n);

        _bstr_t strCmd_n = "insert into n(材料,折射率) values  ('" + material + L"','" + gender + L"','" + m_addaddre + L"','" + m_addtel + L"','" + m_addgrade + L"','" + m_addclassID + L"','" + myuserID + L"')";

        //------------------
        //_bstr_t strCmd_n="insert into n(材料,折射率) values('铁','1.5')";
        //执行SQL命令：insert into...values...插入信息
        m_pConnection->Execute(strCmd_n,&RecordsAffected,adCmdText);
        UpdateData(false);
        MessageBox(L"over");

错误原因：类型出错，加L

UpdateData();
        CString n;
        n.Format(L"%d", m_n);

        _bstr_t strCmd_n = L"insert into n(材料,折射率) values  ('" + material + L"','" + n + L"')";

        //------------------
        //_bstr_t strCmd_n="insert into n(材料,折射率) values('铁','1.5')";
        //执行SQL命令：insert into...values...插入信息
        m_pConnection->Execute(strCmd_n,&RecordsAffected,adCmdText);
        UpdateData(false);
        MessageBox(L"over");