$db = new mysqli($host, $user, $password, $database)
or die("Error " . mysqli_error($db));

$sql = "SELECT name, password FROM login WHERE name = '".addslashes($login_admin->nickname)."'";
$res = $db->query($sql);
$user = $res->fetch_assoc($res);
if($login_admin->password == $user->password){
    echo "Ok";
}else{
    echo "faslse";
}