modelHomework/DB.php

<?php

/**
 * Created by PhpStorm.
 * User: root
 * Date: 31.07.18
 * Time: 10:50
 */
class DB
{
    private static $instance;
    private $connection;
    private static $db_host = '127.0.0.1';
    private static $db_name = 'library';
    private static $db_user = 'root';
    private static $db_pass = 'root';

    private function __construct()
    {
        $this->connection = new PDO(
            'mysql:host=' . self::$db_host .
            ';dbname=' . self::$db_name, self::$db_user, self::$db_pass);
    }

    public static function getConnection()
    {
        if (!self::$instance instanceof self) {
            self::$instance = new self();
        }
        return self::$instance->connection;
    }

    private function __clone()
    {
    }
}