I made my first script of MySQLi. I have just learnt it from 3rd party website. So, I am not sure i am using functions which are not deprecated or outdated. I should start to practice good scripts to access databases. So, I have posted here. Any mistake you see, please point it out.<?phpinclude functions.php;$a = checkLogin();if($a==1) {    $id = $_COOKIE['id'];    include databaseConnector.php;    $query = $mysqli->query(SELECT * FROM users WHERE id = '$id') or die($mysqli->error.__LINE__);    if($query->num_rows > 0) {        while($row = $query->fetch_assoc()) {?>            <?php echo stripslashes($row['firstname']). .stripslashes($row['lastname']); ?>   <?php        }    }    else {        return false;       }}else {    redirectIndex();}?>
MySQLi Code Review for methods and functions used
php;mysqli