Using prepared MySQLi statements to produce associative array - php

Question

I've read a few related questions to this, but in each case I've been unable to get their code to work in my context.
Following some injection attempts, I am trying to implement prepared statements into my site, while changing as little code as possible. Importantly, I want the responses to my SELECT queries to by outputted as associative arrays: e.g. $row['name'].
Here is an example of code that I have right now (without preprepared statements):
// Create connection
$db = new mysqli('localhost', 'username', 'password', 'seatingplan');
if($db->connect_errno > 0){
die('Unable to connect to database [' . $db->connect_error . ']');
}
// Get class name
$sql = <<<SQL
SELECT *
FROM `class`
WHERE `userid` = '$userid'
AND `classid` = '$classid'
SQL;
if(!$result = $db->query($sql)){
die('There was an error running the query [' . $db->error . ']');
}
while($row = $result->fetch_assoc()){
$classname = $row['classname'] ;
}
Is there a straightforward way of adapting this for prepared statements? Based on other questions, this is as far as I've got (but it doesn't work - it only returns 1 for each row, rather than the actual variable):
$stmt = $db->prepare("SELECT *
FROM `class`
WHERE `userid` = ?
AND `classid` = ?");
$stmt->bind_param("ss", $userid, $classid);
$result = $stmt->execute();
$stmt->store_result();
while($data = $stmt->fetch()){
echo $data ;
}

Answer 1

Just define the array and use it for example in your code:
$stmt = $db->prepare("SELECT *
FROM `class`
WHERE `userid` = ?
AND `classid` = ?");
$stmt->bind_param("ss", $userid, $classid);
$stmt->execute();
$result=$stmt->get_result();
$row= array();
$i=0;
while ($data = $result->fetch_assoc())
{
$row[$i]['name']=$data['name'];
$i++;
}
echo $row;