private void btnsubActionPerformed(java.awt.event.ActionEvent evt) {
        Connector kn = new Connector();
        kn.ConnectDB("thongtin");
        try
        {
            ResultSet rs = kn.Laydl("dangnhap", "Username ='"+txtu.getText().trim()+"'AND Password ='"+txtp.getText().trim()+"'");
            rs.last();
            if(rs.getRow()<=0)
            {
                JOptionPane.showMessageDialog(null, "Sai ten dang nhap hoac mat khau");
                return;
            }
            else
            {
                DSCV ds =new DSCV();
                ds.setVisible(true);
                this.setVisible(false);
            }
        }
        catch(Exception e)
        {
            JOptionPane.showMessageDialog(null, "Loi dang nhap !");
        }
    }