MySQLi查询在Webspace上不起作用

Question

Im using mysqli on my localhost it works just fine, but when i upload it to my web server, the page just gets white and nothing else happens.Now i am here to ask for help if you can check on this only function i have in "functions.php" if i remove this function the page loads and if i add it back, the page gets white.

function getUserName($userID) { 
        global $mysqli; 
        $userID = $mysqli->real_escape_string($userID);
        $sql = $mysqli->query("SELECT * FROM users WHERE userID='".$userID."' LIMIT 1"); 
        if ($sql->num_rows > 0) { return $sql->fetch_assoc()['username']; }
        else { return 0; }
    }

And in the index.php i have the connection before this row.

Answer 1

The below line maybe the problem.

return $sql->fetch_assoc()['username'];

Function array dereferencing syntax comes with PHP 5.4, your server's php version may be below than 5.4.

Just check the log in the server and it will be clear.