MySQL PHP Connection Manager

DBConnection.php

class DBConnection{

	private static $DB_SERVER = "localhost";
	private static $DB_USER = "root";
	private static $DB_PASS = "";
	private static $DB_NAME = "db_name";
	
	private $con;
	private $result;
	private $numRows;

	public function __construct(){
		$this->con = new mysqli(self::$DB_SERVER, self::$DB_USER, self::$DB_PASS, self::$DB_NAME);
		if ( $this->_db->connect_errno ){
			echo "Connection error";
			return;
		}
		$this->con->query("SET NAMES 'UTF8'");
		$this->con->set_charset('utf-8');
	}

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

	public function executer($sql){
			$this->result = $this->con->query($sql);
			$this->numRows = $this->result->num_rows;
	}
	public function getNumRows(){
		return $this->numRows;
	}
	public function getResultados(){
		$rows = array();
		for($i=0;$i<$this->numRows; $i++){
			$rows[] = $this->result->fetch_assoc();
		}
		return $rows;
	}
}