Question

This code will output the same. My question is, what is the correct way to do this. The first approach or the second? Or there is any better way? I don’t see any advantage of one Class over the other.

<?php
    class Client{
        var $id;
        var $email;

        function __construct($id){
            $this->id=$id;
        }

        public function get_email($db){
            $sql = $db -> prepare(" SELECT email FROM users  WHERE id = ? ");

            $sql -> bind_param('i', $this->id);
            $sql->execute();

            $sql->bind_result($email);

            if ($sql -> fetch()) {
                return $this->email=$email;
            }
            else
            return false;
        }
    }

    class Client_{
        public function get_email($db, $id){
            $sql = $db -> prepare(" SELECT email FROM users  WHERE id = ?");

            $sql -> bind_param('i', $id);
            $sql->execute();

            $sql->bind_result($email);

            if ($sql -> fetch()) {
                return $email;
            }
            else
            return false;
        }
    }
    ?>

index.php

<?php
$Client = new Client(1);
$a = $Client -> get_email($db);

print_r($a);

$Client_ = new Client_();
$b = $Client_ -> get_email($db, 1);

print_r($b);
?>

Answer 1

In second approach it does not make sense to instantiate class, as there is nothing to be stored for future use. So it would be better to use “static class” if varying data is stored somewhere else:

class Client_{
    static public function get_email($db, $id){
        $sql = $db -> prepare(" SELECT email FROM users  WHERE id = ?");

        $sql -> bind_param('i', $id);
        $sql->execute();

        $sql->bind_result($email);

        if ($sql -> fetch()) {
            return $email;
        }
        else
        return false;
    }
}

// And use it static way without instantiating first:
Client_::get_email( $arg1, $arg2 );

If i shoul make decision between those two I’m going to take first one.

I dont know how you are going to use either one of those classes but still for me it makes more sense to store $db and supply $id from outside and make $email local:

class Client{
    var $db;

    function __construct($db){
        $this->db=$db;
    }

    public function get_email($id){
        $sql = $this->db -> prepare(" SELECT email FROM users  WHERE id = ? ");

        $sql -> bind_param('i', $id);
        $sql->execute();

        $sql->bind_result($email);

        if ($sql -> fetch()) {
            return $email;
        }
        else
        return false;
    }
}

Also changed this line: return $this->email=$email;, maybe I got it wrong but I think that it just doesn’t make sense.