Transitioning to PDO/MySQL. Need help with SELECT statement with LEFT JOIN

I need assistance with a left join on a a SELECT statement.  I am not getting any errors, however, I am not getting any results either...

$conn = new PDO("mysql:host=$host;dbname=$db;charset=$charset", $user, $pass);

$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

// Establish a MySQL connection
	
	$query2 = $conn->prepare('SELECT * FROM `product`
			LEFT JOIN `product_description`
			USING (product_id)
			LEFT JOIN url_alias
			USING (query)');
	
    while ($row2 = $query2->fetch(PDO::FETCH_ASSOC))
    {
		
	 echo $row2['product_id']."  ".$row2['description']."  ".$row2['query'];
	  
	}	

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