Failed to open database.

<?php

class vfsdb {
	
	public $db;

	public function __construct(){
		return true;
	}

	public function open(){
		try {
			$this->db = new mysqli(DBHOST, DBUSER, DBPASSWORD, DBNAME);	
		} catch (Exception $e){
			failure($e->getMessage(), '<p>500 Server Failure</p>', false, '<h1>Failed to open database.</h1>');
		}

		if ( $this->db->connect_errno() ){
			failure("<p>Can't connect to the database. MySQL gave this error code: ".$this->db->connect_errno . "</p>", '500 Server Failure', false, '<h1>Connection to MySQL server failed.</h1>');
		}

		if ( ! $this->db->ping() ){
			failure("<p>Can't reach MySQL server. Server says: " . $this->db->error . "</p>", '500 Server Failure', false, "<h1>Can't reach MySQL server!</h1>");
		}

		if ( ! $this->db->set_charset(DBCHARSET) ){
			failure("<p>Can't set UTF-8 as a charset on your MySQL server." , '500 Server Failure', false, "<h1>Setting Charset failed!</h1>");
		}

	}

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

	public function check(){
		if ( ! $this->db->ping() ){
			return false;
		}

		return true;
	}

	private function _prepare($sql){
		if ( is_null($sql) || $sql == "")
			return false;

		return $this->db->real_escape_string($sql);
	}

	public function doQuery($string){
		if ( ! $this->check() )
			failure("<p>Can't reach MySQL server. Server says: ". $this->db->error . "</p>", '500 Server Failure', false, "<h1>Can't reach MySQL server!</h1>")

		$sql = _prepare($string);
		if ( ! $sql )
			return false;
		return $this->db->query($sql);
	}

	public function setUp(){
		$user_table = 
		'CREATE TABLE IF NOT EXISTS ' . DBPREFIX . 'user 
			( id INTEGER AUTO_INCREMENT NOT NULL, PRIMARY KEY(id), 
			name VARCHAR(70), UNIQUE(name), 
			password VARCHAR(70), UNIQUE(password), 
			email VARCHAR(70), UNIQUE(email), 
			invites INTEGER, 
			inviter INTEGER, 
			invitekey VARCHAR(70), UNIQUE(invitekey), 
			status INTEGER, 
			color_folder VARCHAR(70), 
			color_file VARCHAR(70))
		ENGINE=InnoDB;'
		$files_table = 
		'CREATE TABLE IF NOT EXISTS ' . DBPREFIX . 'files
			( files_id INTEGER AUTO_INCREMENT NOT NULL, PRIMARY KEY(files_id),
			parent INTEGER,
			owner INTEGER,
			name VARCHAR(70),
			type VARCHAR(70),
			mime VARCHAR(70),
			size INTEGER,
			visibility VARCHAR(70),
			hash VARCHAR(70),
			download_link VARCHAR(70),
			upload_time INTEGER,
			last_access INTEGER,
			FOREIGN KEY(files_id) REFERENCES user(id) ON DELETE CASCADE
			)
		ENGINE=InnoDB;'
		$banned_user_table = 
		'CREATE TABLE IF NOT EXISTS ' . DBPREFIX . 'banned_user
			( banned_id INTEGER AUTO_INCREMENT NOT NULL, PRIMARY KEY(banned_id),
			login_attempts INTEGER,
			ip TEXT,
			session_id TEXT,
			time INTEGER,
			user INTEGER
			)
		ENGINE=InnoDB;'

		if ( ! $this->db->query($user_table . ' ' . $files_table . ' ' . $banned_user_table) )
			failure("<p>Setting up the database failed.</p>", '500 Server Failure', false, "<h1>CREATE TABLE FAILED");
	}
	
	public function __destruct(){
		$this->close();
	}
}