Select empty data

My code returns all users, verifying that they have paid the last month, however I connect two tables, one of all the clients with the registered payment table, I want it to print in jTable even if it does not have left join seems to be playing the same role as inner join , follows the piece of code:

public void preencherTabela(){
    ArrayList dados = new ArrayList();
    String [] Colunas = new String[]{"CPF", "NOME", "DATA", "PAGO"};

    try{
        Connection con = Conexao.getConexao();
        Statement stmt = con.createStatement();
        ResultSet RS = stmt.executeQuery("Select cadastrarpac.nome, cadastrarpac.cpf, max(pagamento.data) from cadastrarpac "
                + "left join pagamento on (cadastrarpac.IdPac=pagamento.id_pac)");
        while(RS.next()){
            String nome = RS.getString("nome");
            String cpf = RS.getString("Cpf");
            String data = RS.getString("max(pagamento.data)");
            Date date = new SimpleDateFormat("dd/MM/yyyy").parse(data);  
            int data2 = date.getMonth()+1;
            SimpleDateFormat df = new SimpleDateFormat("dd/MM/yyyy");
            Date now = new Date();
            int data3 = now.getMonth()+1;


            boolean pago;   
            if (data2==data3){
                pago=true;
            if (data.isEmpty()){
                pago=false;
            }
            }else{
                pago=false;
            }

            dados.add(new Object[]{cpf, nome, data, pago});
        }
    }catch(Exception e){

    }
    ModeloTabela modelo = new ModeloTabela(dados, Colunas);
    table.setModel(modelo);
    table.getColumnModel().getColumn(0).setPreferredWidth(80);
    table.getColumnModel().getColumn(0).setResizable(false);
    table.getColumnModel().getColumn(1).setPreferredWidth(176);
    table.getColumnModel().getColumn(1).setResizable(false);
    table.getColumnModel().getColumn(2).setPreferredWidth(75);
    table.getColumnModel().getColumn(2).setResizable(false);
    table.getColumnModel().getColumn(3).setPreferredWidth(80);
    table.getColumnModel().getColumn(3).setResizable(false);
    table.getTableHeader().setReorderingAllowed(false);
    table.setAutoResizeMode(table.AUTO_RESIZE_OFF);
    table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
}

Tabela pagamento:
id_pag int not null primary key, //id do registro de pagamento
id_pac int not null              //id do paciente(cliente)
data varchar(80) not null        //data do pagamento

insert into pagamento (id_pac, data) values (1, 20/04/2016)
insert into pagamento (id_pac, data) values (2, 21/04/2016)

Tabela cadastrarpac:
IdPac int not null primary key, //id do paciente 
Cpf varchar(12) not null,       //cpf 
Nome varchar(80) not null       //nome

insert into cadastrarpac (Cpf, Nome) values (088.758.960-0, Matheus) //id 1
insert into cadastrarpac (Cpf, Nome) values (089.858.966-0, Miriam)  //id 2

Any help is welcome, Thanks