Warning: mysqli_query() expects at least 2 parameters, 1 given in...

private $db_host = 'localhost';
	private $db_user = 'root';
	private $db_pass = 'root';
	private $db_name = 'my_db'; 
	
	//--- connect --->
	public function connect(){
		try{
			if(!$this->con){
				$myconn = mysqli_connect($this->db_host,$this->db_user,$this->db_pass);// or die(mysqli_error());
				if($myconn){
					$seldb = mysqli_select_db($myconn,$this->db_name);
					mysqli_query($myconn,"SET NAMES UTF8");
					if($seldb){
						$this->con = true;
						return true;
					}else{
						return false; //mysql_error();
					}				
				}else{
					return false; //mysql_error();
				}
			}else{
				return false; //mysql_error();
			}
		}catch(Exception $e){
			return $e;
		}
	}