php mysql echo值，表中包含最高计数器

Question

I have a mySQL table PRERENDER like this

id | canonical     | prerender      | count
------------------------------------------------
01 | example.com/1 | Example.com/23 | 12

02 | example.com/1 | Example.com/54 | 10

03 | example.com/2 | Example.com/5  | 12
...

canonical + prerender are an index, the couple can't be duplicated. if the couple already exists so add +1 to count

What I need:

I need to get

when active URL = $canonical get the prerender field with the highest counter.

this is what I try:

 $canonical="https://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
 $sql2 = mysql_query('
 SELECT prerender 
 FROM PRERENDER 
 WHERE (canonical = '.$canonical.') AND (count = MAX(count))
 ';

Any tips?

CODE UPDATE

$servername = "xxx";
$username = "xxx";
$password = "xxx";
$dbname = "xxx";
$referral=$_SERVER['HTTP_REFERER'];
$referral = strtok($referral, '?');
$canonical="https://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
$conn = new mysqli($servername, $username, $password, $dbname);
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
if ((strpos($referral, 'evemilano.com') !== false)) {
$sql = "INSERT IGNORE INTO PRERENDER (ID,canonical,prerender,count) VALUES (NULL,'$referral','$canonical','1') ON DUPLICATE KEY UPDATE count = count +1         ";
}
if (!mysqli_query($conn, $sql)) {    printf("Errormessage: %s
", mysqli_error($conn));}

$sql2 = "SELECT prerender FROM PRERENDER WHERE canonical = '$canonical' ORDER BY count desc limit 1";
echo 'pre: ';
$result= mysqli_query($conn, $sql2);
foreach($result as $row)
{
echo $row['prerender'];
}

UPDATE: now it works

Answer 1

SELECT `prerender` FROM `PRERENDER` WHERE (`canonical` = '.$canonical.')
ORDER BY `count` DESC LIMIT 1