MFC登录界面对话框连接数据库代码

void CUserLoadDlg::OnBnClickedBtnload()
{
    // TODO: 在此添加控件通知处理程序代码
    UpdateData(TRUE);
    if(m_Name.IsEmpty() || m_PassWord.IsEmpty())
    {
        MessageBox("用户名或密码不能为空");
        return;
    }
    m_Num++;
    CString sql;
    sql.Format("select * from tb_user where username = '%s' and pwd = '%s'",
        m_Name,m_PassWord);
    m_LoginSet = new Ctb_user(&((CMystudentsysApp*)AfxGetApp())->m_DB);
    if(!m_LoginSet->Open(AFX_DB_USE_DEFAULT_TYPE,sql))
    {
        AfxMessageBox("tb_studentinfo 表打开失败!");
    }
    if(m_LoginSet->GetRecordCount()!=0)
    {
        CDialog::OnOK();
    }
    else
    {
        if(m_Num == 3)
        {
            MessageBox("密码3次不正确");
            CDialog::OnCancel();
        }
        else
        {
            MessageBox("用户名或密码不正确");
            m_Name = "";
            m_PassWord = "";
            UpdateData(FALSE);
        }
    }
    if(m_LoginSet->IsOpen())
    {
        m_LoginSet->Close();
        delete m_LoginSet;
    } 
}