Php simple search engine?

I'm building a search engine that returns data and I'm having trouble displaying a message if there's no results in the database. I'm a beginner at MYSQLI. how would I do something like that? I tired counting the rows and if they're less then 0 to display it but I was having bugs while writing it.

Code:

<?php
$db = mysqli_connect('localhost','root', '', 'searchengine');

if(!$db) {
    die('sorry we are having some problbems');
}


$searchTerm = mysqli_real_escape_string($db,$_GET['term']);

$searchTerm = trim($searchTerm);

if ($searchTerm == '') {
    echo("no key words searched please try again");
}

else
{
$sql = mysqli_query(
    $db,
    sprintf(
        "SELECT * FROM searchengine WHERE name LIKE '%s' LIMIT 0,20",
        '%'. $searchTerm .'%'
    )
);

while($ser = mysqli_fetch_array($sql)) {
    echo "<a href='$ser[pageurl]'>$ser[img]</a>";
}
}

mysqli_close($db);
?>
Copy code