php mysql : how to avoid multiple connections to database in a Class?

Question

Here is my index.php

<?
require("Annonce.php");
$annonce = new Annonce();
$annonce->id=1;
$annonce->delete();

?>

My Annonce.php is!

<?php 

require("DB.php");
class Annonce extends DB {
}    
 ?>

and finally DB is:

<?php 
$db = new PDO('mysql:host=localhost;dbname=annonces;charset=utf8', 'root', '');
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);


class DB {
    public static $debug = true;    
    function __construct() {
        # code...
    }
    function delete() {
        $id = $this->id;
        $table = get_class($this);
        $sql="delete from $table where id=$id";     
        if ($this::$debug) echo $sql;

    }

    function get() {
        $sql="select *...";
    }

}
 ?>

I don't know what is the best strategy to define the $db connection ?

If I define it inside DB class, it will make a connection any time an "Annonce" object is created. Maybe using $db as GLOBAL (which I think is not clean)

Any suggestion for that ?

Maybe you will be interested by the [Singleton pattern](http://php.net/manual/de/language.oop5.patterns.php). — Debflav, Mar 14 '14 at 10:03

score 1 · Answer 1 · answered Mar 14 '14 at 10:07

Create a Singleton ,some thing like this:

class DB
{
   private $_db;
   private $_instance;
   private function __construct() 
   {

    $this->_db = $db = new PDO('mysql:host=localhost;dbname=annonces;charset=utf8', 'root', '');

}

public static function getInstance()
{
    if(!(self::$_instance instanceof DataBase)){
      $c = __CLASS__;
      self::$_instance = new $c;
    }
    return self::$_instance;
}
//.....other code

}

use it by :

$db = DB::getInstance();

score 0 · Answer 2 · edited May 23 '17 at 12:29

You could define your connection as a service and use a Dependency Injuection Container (DIC) to provide the connection for any other feature/module/class needing it by providing the Dependency Injection Container. Pimple is a simple DIC Solution by "the people who brought us Symfony".

Having a DIC is a good idea anyway.

THis might seem "over the top" for your problem (since a Singleton would definetly solve your problem) but considering a DIC will improve your work a lot more. And you asked for a clean Solution. The Singleton Design Pattern is only clean if you do not use Unit Tests since Singletons will get you into trouble with mocking.

php mysql : how to avoid multiple connections to database in a Class?

2 Answers2