Java/SQL Login and Password Validation Issue

Question

I have a problem in the validation of Login and Password, the code is only taken the values of the first line of the database, but when I try to put the values of the other lines it gives error, I appreciate if someone can help me. Follow the code below.

try{
    Connection con = BancoSQL.getConexao();
    String sql = "select Login, Senha from cadfuncionario";
    PreparedStatement ps = con.prepareStatement(sql);
    ResultSet rs = ps.executeQuery(sql);

    String login = jUsuario.getText();
    String senha = jSenha.getText();

    while(rs.next()){

        if(rs.getString("Login").equalsIgnoreCase(login) 
        && rs.getString("Senha").equalsIgnoreCase(senha)){

            this.dispose();
            MenuP m = new MenuP();
            m.setVisible(true);
            JOptionPane.showMessageDialog(null,"Bem vindo");
            break;

        }else{

            JOptionPane.showMessageDialog(null,"Usuario ou Senha Incorretos!");
            jUsuario.setText("");
            jSenha.setText("");
        }

    }
    }catch(Exception e){ e.printStackTrace(); }

Answer 1

I suggest you take advantage of Preparedstatement and do the following:

PreparedStatement p = con.prepareStatement("select idusuario from usuario where login = ? and senha = ?");
p.setString(1, login);
p.setString(2, senha);
ResultSet r = p.executeQuery();

if(r.next()){
    // Se r.next() for verdade existe uma combinação login/senha               
}

// Nunca esqueça de fechar os fluxos, eles podem acumular.
r.close();
p.close();
con.close();

So the database will return only one line, you would not need to go through all the rows of your registration table (It doesn’t make much sense since there shouldn’t be 2 identical login/password combinations). Also, these "?" of Prepared protect against SQL Injection.

Note: Avoid storing passwords in Plain text in the bank, only save encrypted passwords.

Answer 2

Hello, it seems:

if(rs.getString("Login").equalsIgnoreCase(login) 
 && rs.getString("Senha").equalsIgnoreCase(senha)){

When entering this code block the first time, you call the command

 break;

causing the code to exit the while(rs.next()) and ending the execution of your application. IE, even if you have more than one result will always end in the first line.