public static ArrayList<Customer> getAll(){
        
        SQLiteJDBC db = new SQLiteJDBC();
        ArrayList<Customer> customers = new ArrayList<Customer>();
        
        String sql = "SELECT * FROM customers";
        ResultSet resultSet = db.query(sql);
        
        try {            
            while(resultSet.next()){
                Customer customer = new Customer(resultSet.getInt("user_id"));
                customers.add(customer);
            }
            db.close();
        }catch(Exception e) {
            System.err.println( e.getClass().getName() + ": " + e.getMessage() );
            System.exit(0);
        }
        
        return customers;
    }