MySQL Class Simple

MySQL.php

<?php
class MySQL
{
	var $link;

	function __construct()
	{
		include_once dirname(__FILE__) . '/config.php';
		$this->link = mysqli_connect(
			config\MYSQL_HOST,
			config\MYSQL_USERNAME,
			config\MYSQL_PASSWORD,
			config\MYSQL_DB,
			config\MYSQL_PORT
		);
		mysqli_set_charset($this->link, "utf8mb4");
	}

	public function query()
	{
		//var_dump($this->prepareQuery(func_get_args()));
		return mysqli_query($this->link, $this->prepareQuery(func_get_args()));
	}

	/* Security methods */
	protected function prepareQuery($args)
	{
		$query = '';
		$raw = array_shift($args);
		$array = preg_split('~(\?[nsiuap])~u', $raw, null, PREG_SPLIT_DELIM_CAPTURE);
		foreach ($array as $i => $part) {
			if (($i % 2) == 0) {
				$query .= $part;
				continue;
			}
			$value = array_shift($args);
			switch ($part) {
				case '?i':
					$part = $this->escapeInt($value);
					break;
				case '?s':
					$part = $this->escapeString($value);
					break;
			}
			$query .= $part;
		}
		return $query;
	}

	protected function escapeInt($value)
	{
		if ($value === NULL) {
			return 'NULL';
		}
		if (!is_numeric($value)) {
			$this->error("Integer (?i) placeholder expects numeric value, " . gettype($value) . " given");
			return FALSE;
		}
		if (is_float($value)) {
			$value = number_format($value, 0, '.', '');
		}
		return $value;
	}

	protected function escapeString($value)
	{
		if ($value === NULL) {
			return 'NULL';
		}
		return "'" . mysqli_real_escape_string($this->link, $value) . "'";
	}
}