Bugs and Suggestions

void CPeopleCounterDlg::OnBnClickedbtnlogin()
{
    UpdateData();
    bool ValidLogin = false;

    if( m_Username == "" )
    {
        AfxMessageBox("You must provide a username to Login.");
        m_EditUsername.SetFocus();

        return;
    }
    if( m_Password == "" )
    {
        AfxMessageBox("Please enter your password.");
        m_EditPassword.SetFocus();
        return;
    }
            //SQL查询语句
        if(mysql_query( ssock,"SELECT * FROM user WHERE Username == \"m_Username\" AND Password == \"m_Password\" "))
        {
            ValidLogin = true;
            CPplCMain  m_pplc;
            m_pplc.DoModal();
            this->ShowWindow(SW_HIDE);
            this->ShowWindow(SW_SHOW);
        }
        if(ValidLogin = false){
            MessageBox("Invalid login!");
        }
        if( !(res = mysql_store_result(ssock)) )
    {
        MessageBox("Disconnected!", mysql_error(ssock));
    }
    UpdateData(FALSE);
    mysql_close(ssock);
}