PDO class design

Question

I have the following class design for my PDO database access class. Please can someone confirm that this is good practice, or suggest improvements if necessary.

Thanks.

Database.php

class db {
    private $conn;

    public function __construct() {
        $this->conn = new PDO(...);
    }

    $conn = new db();
}

Class.php

// require Database.php

class someClass {
    private $conn;

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

    function myFunc($usr, $pwd) { 
        // SQL
    } 
}

Main.php

// require Class.php
$myObj = new someClass($conn);

$myObj->myFunc(PARAMS);

Answer 1

Your db class is not valid

You can't have a variable assignment in a class outside a function. $conn = new db(); is not a valid syntax unless you put it in a function. Also recreating the same class inside that class does not make sense.

Is it providing any benefits

Is your database class adding any new functionality to the PDO class? If not, there is no point in doing what you do unless you want to create a wrapper around PDO.

Answer 2

Might be easier to just extend the PDO class to do what you want.

i.e.

class db extends \PDO {}

class foo {
    private $conn;

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

    // ALL OTHER NEW METHODS
}

require Database.php
$conn = new db(PARAMS);

require Foo.php
$foo = new foo($conn);
$foo->someMethod();

This is assuming that you will have functionality OVER-AND-ABOVE what the PDO class does. If you DO NOT, there is no reason to extend the PDO class.