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

Saya ada error di bagian Warning: mysqli_query() expects at least 2 parameters, 1 given in /opt/lampp/htdocs/FIX/soal/session_soal.php on line 6 Warning: mysqli_error() expects exactly 1 parameter, 0 given in /opt/lampp/htdocs/FIX/soal/session_soal.php on line 6 Warning: mysqli_error() expects exactly 1 parameter, 0 given in /opt/lampp/htdocs/FIX/soal/session_soal.php on line 6.

tolong di bantu ya kak. saya masih newbie

ini source code nya

 ?php

include '../login/db.php';
session_start();

$query = mysqli_query("SELECT * FROM bank_exam") or die (mysqli_error());
$_SESSION['id_exam'] = 1;
$_SESSION['id_training'] = array();
$_SESSION['levels'] = array();
$_SESSION['questions'] = array();
$_SESSION['options'] = array();
$_SESSION['answers'] = array();
$i=0;
	while ($row = mysqli_fetch_assoc($query)) {
		$_SESSION['questions'][] = $row;
		$_SESSION['options'][] = array($_SESSION[$i]['a'],$_SESSION['questions'][$i]['b'],$_SESSION[$i]['c'],$_SESSION[$i]['d']);
		$i++;
	}

		if (isset($_SESSION['questions'])) {
			header("location:index.php");
		}
?>