Unable to get COUNT(*) result from structured SQL statement - php

Question

I've been working on a SQL statement that checks the database to see if feedback has been left for a specific qr_id from a specific uuid within 24 hours. The original code works as intended, but obviously to be more secure I wanted to change the code to a structed SQL statement instead.
$uuid = "DB8962A3-BC7A-481F-9D7E-C1FC7F74E50E";
$qrid = "2147483647";
$query = sprintf("SELECT COUNT(*) FROM `feedback` WHERE uuid = '%s' AND qr_id = '%s' AND created_on > UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 1 DAY))", mysql_real_escape_string($uuid), $qrid);
$result = mysql_query($query);
$row = mysql_fetch_assoc($result);
$size = $row['COUNT(*)'];
if ($size > 0){
echo 'Unable to leave feedback as user has left feedback for this employee within 24 hours.';
}else{
echo 'User has not left feedback for this employee within 24 hours, continue.';
}
The above works perfectly fine, if the count is above 0 then it stops the user posting. Here's my attempt at converting it to a structured SQL statement:
$stmt = $this->conn->prepare("SELECT COUNT(*) FROM `feedback` WHERE uuid = ? AND qr_id = ? AND created_on > UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 1 DAY))");
$stmt->bind_param('si', $uuid, $qrID);
$result = $stmt->execute();
$size = $result['COUNT(*)'];
$stmt->close();
if ($size = 0){
// do post, return true
return true;
}else{
return false;
// do not post, return false
}
I have tried printing the result value and it's always 1, and trying to echo the $size variable returns nothing.

Answer 1

You need to fetch the result, try this:
$stmt->bind_param('si', $uuid, $qrID);
$stmt->execute();
//here you bind result to variable $size
$stmt->bind_result($size);
$stmt->fetch()
$stmt->close();
if ($size == 0){
// do post, return true
return true;
}else{
return false;
// do not post, return false
}