Database.php

<?php

/*
* class contains database management functions used all over the script
*/
class Database extends Common {

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

    function __destruct() {
        $this->closeDatabaseConnection();
    }

    private function openDatabaseConnection()
    {
        $this->db = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
        if ($this->db->connect_errno) {
            echo "Failed to connect to MySQL: " . $this->db->connect_error;
            die();
        }
        $this->db->set_charset(DB_CHARSET);     
    }

    private function closeDatabaseConnection()
    {
        $this->db->close();    
    }

}