idPenjualan

private void genIdTransaksi(){
        try{
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            Date date = new Date();
            String now = sdf.format(date);
            SimpleDateFormat df = new SimpleDateFormat("ddMMyy");
            String hasil = df.format(date);
            String SQL = "select tanggal from penjualan where tanggal = '"+now+"' and substring(idPenjualan,6,6)='"+sesi.getIdKasir()+"'";
            ResultSet r = koneksi.executeQuery(SQL);
            if(r.next()){
            String SQL1 = "select substring(idPenjualan,1,4) as id "
                    + "from penjualan where tanggal ='"+now+"' "
                    + " and substring(idPenjualan,6,6)='"+sesi.getIdKasir()+"' order by idPenjualan desc limit 0,1";
            ResultSet rs = koneksi.executeQuery(SQL1);

            if(rs.next()){
                String str = "0000";
                int id = Integer.valueOf(rs.getString(1))+1;
                String str_no = String.valueOf(id);
                String idTransaksi = str.substring(0,4-str_no.length())+Integer.toString(id)+"-"+sesi.getIdKasir()+"-"+hasil;
                System.out.println(idTransaksi);
                txtIdTransaksi.setText(idTransaksi);
            }
            }else{
                txtIdTransaksi.setText("0001"+"-"+sesi.getIdKasir()+"-"+hasil);
            }
        }catch(Exception e){
            JOptionPane.showMessageDialog(rootPane, "Ada kelasahan dalam database");
            System.out.println(e);
        }
    }